Class 12th VVI Physics EM - Science Sangrah

* { box-sizing: border-box; padding: 0;margin: 0; } /* Create two equal columns that floats next to each other */ .column { float: left; width: 50%; padding: 10px; } /* Clear floats after the columns */ .row:after { content: “”; display: table; clear: both; } /* Style the buttons */ .btn { border: none; outline: none; padding: 12px 16px; background-color: #f1f1f1; cursor: pointer; } .btn:hover { background-color: #ddd; } .btn.active { background-color: #666; color: white; } .ques { font-size: 20px; } .ans { font-size: 16px; color: white; background: #ff5733; width: 45%; text-align: center; padding-top: 9px; padding-bottom: 9px; } @media only screen and (max-width: 768px) { /* For mobile phones: */ [class*=”col-“] { width: 100%; } }

1. Electric Charge & Field Test

OBJECTIVE QUESTIONS

1. When a body is charged, its mass-

[ A ] Increases

[ B ] Decreases

[ C ] Remains same

[ D ] May increase or decrease

Answer ⇒ (D)

2. At what angle do two electric field lines intersect each other?

[ A ] 90 degree

[ B ] 45 degree

[ C ] 30 degree

[ D ] Do not intersect

Answer ⇒ (D)

3. Electric field is

[ A ] Conservative

[ B ] Non-conservative

[ C ] Somewhere Conservative and Somewhere Non-conservative

[ D ] None of these

Answer ⇒ (A)

4. Which of the following is a vector?

[ A ] Charge

[ B ] Capacity

[ C ] Electric field intensity

[ D ] None of these

Answer ⇒ (C)

5. When a soap bubble is charged, its radius

[ A ] Increases

[ B ] Decreases

[ C ] Remains the same

[ D ] Becomes zero

Answer ⇒ (A)

6. Which of the following has unit (volt)/(metre) ?

[ A ] Electric flux

[ B ] Electric potential

[ C ] Electric capacity

[ D ] Electric field

Answer ⇒ (D)

7. Which of the following is a vector?

[ A ] Charge

[ B ] Capacity

[ C ] Electric field intensity

[ D ] None of these

Answer ⇒ (C)

8. Which of the laws gives the force between two charges at rest?

[ A ] Gauss theorem

[ B ] Kirchhoff’s rules

[ C ] Coulomb’s law

[ D ] Faraday’s laws

Answer ⇒ (C)

9. The S.I. unit of electric charge is

[ A ] Ampere

[ B ] Farad

[ C ] Volt

[ D ] Coulomb

Answer ⇒ (D)

10. If the distance between two charged particles is doubled, the force between them

[ A ] Gets doubled

[ B ] Gets halved

[ C ] Gets quadrupled

[ D ] Becomes one-fourth

Answer ⇒ (D)

2. Electrostatic Potential & Capacitance Test

OBJECTIVE QUESTIONS

1. The quantity which remains the same in series combination of capacitors is

[ A ] Charge

[ B ] Energy

[ C ] Potential difference

[ D ] Capacitance

Answer ⇒ (A)

2. In parallel combination of capacitors, quantity which remains the same for every capacitor is

[ A ] Charge

[ B ] Energy

[ C ] Potential difference

[ D ] Capacitance

Answer ⇒ (A)

3. Three capacitors, each of capacitance C, are connected in parallel. Their equivalent capacitance will be

[ A ] 3/C

[ B ] 3C

[ C ] 1/2C

[ D ] C/3

Answer ⇒ (B)

4. If an electric dipole is kept in a uniform electric field then resultant electric force on it is

[ A ] Always zero

[ B ] Never zero

[ C ] Depends upon capacity of dipole

[ D ] None of these

Answer ⇒ (A)

5. A charged conductor is in electrostatic condition. At a point inside the conductor

[ A ] Potential is zero

[ B ] Potential gradient is zero

[ C ] Electric field gradient is not zero

[ D ] Any two of A, B and C

Answer ⇒ (B)

6. If electron has a charge of value e and mass m, and it moves under potential difference V, its kinetic energy will be

[ A ] meV Joule

[ B ] eV/m Joule

[ C ] eV Joule

[ D ] None of these

Answer ⇒ (C)

7. If two conducting sphere are connected after charging separately then

[ A ] Stored energy in spheres will remain conserved

[ B ] Total of charge remains conserved

[ C ] Both stored charge remains conserved

[ D ] None of these

Answer ⇒ (B)

8. If an earthed conductor is brought near an insulated conductor, then the capacity of insulated conductor

[ A ] Decreases

[ B ] Increases

[ C ] Remains unchanged

[ D ] None

Answer ⇒ (B)

9. If a conductor is placed in an electric field, the electric field inside the conductor

[ A ] Decreases

[ B ] Increases

[ C ] Becomes zero

[ D ] Remains unchanged

Answer ⇒ (C)

10. Van de Graff generator is a machine that produces

[ A ] AC power

[ B ] Current of high frequency

[ C ] Voltage of several lakh volts

[ D ] Only small current

Answer ⇒ (C)

3. Current Electricity Test

OBJECTIVE QUESTIONS

1. The S.I unit of resistance is

[ A ] Weber (Wb)

[ B ] Henry (H)

[ C ] Ampere (A)

[ D ] Ohm (Ω)

Answer ⇒ (D)

2. The emf of a call can be measured by

[ A ] A voltmeter

[ B ] An ammeter

[ C ] A galvanometer

[ D ] A potentiometer

Answer ⇒ (D)

3. The emf of a dry cell is 1.5 V and internal resistance is 0.5Ω. Ohm If it sends current of 1A in an external resistance, its potential difference is

[ A ] 1.5 V

[ B ] 1 V

[ C ] 0.5 V

[ D ] 0 V

Answer ⇒ (B)

4. To analyze the network of conductors, one uses

[ A ] Ohm’s law

[ B ] Kirchoff’s law

[ C ] Joule’s law

[ D ] Faraday’s law

Answer ⇒ (B)

5. The algebraic sum of all the current at a point in an electric circuit is

[ A ] Zero

[ B ] Infinity

[ C ] Positive

[ D ] Negative

Answer ⇒ (A)

6. Wheatstone bridge is used for measuring

[ A ] High resistance only because joints have a resistance of the order of 1Ω ohm

[ B ] Low resistance only

[ C ] Both high and low resistances

[ D ] Potential difference

Answer ⇒ (A)

7. The temperature of electric bulb just after it is switched on

[ A ] Goes on increases

[ B ] First decreases then decreases

[ C ] First increases then decreases

[ D ] First increases and then becomes constant

Answer ⇒ (D)

8. The resistance of a metal, when heated, goes on

[ A ] Decreases

[ B ] Increases

[ C ] Remaining the same

[ D ] Becoming zero

Answer ⇒ (B)

9. If a uniform wire of resistance 1 ohm is cut into four equal parts and these are connected together in parallel, the equivalent resistance of the combination will be

[ A ] 4 ohm

[ B ] 1 ohm

[ C ] 1/4 ohm

[ D ] 1/16 ohm

Answer ⇒ (D)

10. The Kirchhoff’s point rule obeys the principle of conservation of

[ A ] Energy

[ B ] Charge

[ C ] Momentum

[ D ] Mass

Answer ⇒ (B)

4. Moving Charges and Magnetism Test

OBJECTIVE QUESTIONS

1. The rule to determine the direction of a Lorentz force is

[ A ] Fleming’s left hand rule

[ B ] Fleming’s right hand rule

[ C ] Maxwell’s right handed screw-cork rule

[ D ] Ampere’s swimming person rule

Answer ⇒ (A)

2. The current in a wire is due east and the wire is placed in a north-directed magnetic field, the force on the wire will be directed

[ A ] Eastward

[ B ] Westward

[ C ] Vertically downward

[ D ] Vertically upward

Answer ⇒ (D)

3. In a moving coil galvanometer, coil core is of soft iron so that

[ A ] Magnetic field be uniform

[ B ] Magnetic field be strong and radial

[ C ] Magnetic field be only radial

[ D ] Resistance of coil be zero

Answer ⇒ (B)

4. A charge moving with uniform velocity produces

[ A ] Only an electric field

[ B ] Only a magnetic field

[ C ] Electromagnetic field

[ D ] None of these

Answer ⇒ (C)

5. The magnetic field lines around a straight current are

[ A ] Circular around the current

[ B ] Straight parallel to current

[ C ] Normal to current and straight

[ D ] None of these

Answer ⇒ (A)

6. Tesla is the unit of

[ A ] Electric field

[ B ] Magnetic field

[ C ] Electric flux

[ D ] Magnetic flux

Answer ⇒ (B)

7. To convert a galvanometer into ammeter

[ A ] A low resistance is connected in parallel

[ B ] A high resistance is connected in series

[ C ] A low resistance is connected in series

[ D ] A high resistance is connected in parallel

Answer ⇒ (A)

8. The sensitivity of a galvanometer, when a shunt is connected

[ A ] Decreases

[ B ] Increases

[ C ] Remains unchanged

[ D ] None of these

Answer ⇒ (A)

9. When the number of turns in a moving coil galvanometer is increased while other factors remain the same

[ A ] Current-sensitivity is increased

[ B ] Voltage sensitivity does not change

[ C ] Both a and b

[ D ] None of these

Answer ⇒ (C)

10. When the current in a solenoid is doubled, the magnetic induction in the solenoid

[ A ] Gets doubled

[ B ] Remains the same

[ C ] Becomes half

[ D ] None of these

Answer ⇒ (A)

5. Magnetism and Matter Test

OBJECTIVE QUESTIONS

1. For making an electromagnet, core material should have

[ A ] High magnetic susceptibility

[ B ] High magnetic receptivity

[ C ] High hysteresis area

[ D ] None of these

Answer ⇒ (A)

2. Which of the following show hysteresis ?

[ A ] Paramagnetic

[ B ] Diamagnetic

[ C ] Ferromagnetic

[ D ] None of these

Answer ⇒ (C)

3. Magnetic dipole moment is a vector Quantity directed from

[ A ] South to North pole

[ B ] North to South pole

[ C ] East to West direction

[ D ] West to East direction

Answer ⇒ (A)

4. The area of a magnetic hysteresis loop is directly proportional to

[ A ] Thermal energy developed per unit volume

[ B ] Magnetic field intensity

[ C ] Pole strength

[ D ] None of these

Answer ⇒ (A)

5. A plane mirror is used in a deflection magnetometer to

[ A ] Remove parallax

[ B ] Bring in magnetic meridian

[ C ] To view the needle

[ D ] None of these

Answer ⇒ (A)

6. If suspension string remains twisted it causes an additional torque due to which the oscillation period of magnet is

[ A ] Increased

[ B ] Decreased

[ C ] Doubled

[ D ] None of these

Answer ⇒ (A)

7. The number of neutral points when the north pole of a bar magnet points due to it is

[ A ] 1

[ B ] 2

[ C ] 3

[ D ] None of these

Answer ⇒ (B)

8. Because there is no isolated pole found as yet, the magnetic flux over a closed surface is

[ A ] Zero

[ B ] Positive

[ C ] Negative

[ D ] None of these

Answer ⇒ (A)

9. The magnetic moment of a magnet is

[ A ] Scalar

[ B ] Vector

[ C ] Neutral

[ D ] None of these

Answer ⇒ (B)

10. The direction of magnetic moment M vector is

[ A ] From North Pole to South Pole

[ B ] From South Pole to North Pole

[ C ] Perpendicular to the magnetic axis

[ D ] None of these

Answer ⇒ (B)

6. Electromagnetic Induction Test

OBJECTIVE QUESTIONS

1. Lenz’s law is a consequence of the law of conservation of

[ A ] charge

[ B ] mass

[ C ] energy

[ D ] momentum

Answer ⇒ (C)

2. A magnet is moved towards a coil (i) Quickly (ii) slowly, then the induced e.m.f. is

[ A ] larger in case (i)

[ B ] smaller in case (i)

[ C ] equal to both the cases

[ D ] larger or smaller depending upon the radius of the coil

Answer ⇒ (A)

3. The laws of electromagnetic induction have been used in the construction of a

[ A ] galvanometer

[ B ] voltmeter

[ C ] electric motor

[ D ] generator

Answer ⇒ (B)

4. Two identical coaxial coils P and Q carrying equal amount of current in the same direction are brought nearer. The current in

[ A ] P increases while in Q decreases

[ B ] Q increases while in P decreases

[ C ] both P and Q increases

[ D ] both P and Q decreases

Answer ⇒ (D)

5. Faraday’s laws are consequence of the conservation of

[ A ] Charge

[ B ] Energy

[ C ] Magnetic field

[ D ] Both b and c

Answer ⇒ (B)

6. Direction of current induced in a wire moving in a magnetic field is found using

[ A ] Fleming’s left hand rule

[ B ] Fleming’s right hand rule

[ C ] Ampere’s rule

[ D ] Right hand clasp rule

Answer ⇒ (A)

7. Which of the following statements is not correct?

[ A ] Whenever the amount of magnetic flux linked with a circuit changes, an emf is induced in circuit

[ B ] The induced emf lasts so long as the change in magnetic flux continues

[ C ] The direction of induced emf is given by Lenz’s law

[ D ] Lenz’s law is a consequence of the law of conservation of momentum

Answer ⇒ (C)

8. Lenz’s law is a consequence of the law of conservation of

[ A ] Charge

[ B ] Energy

[ C ] Induced emf

[ D ] Induced current

Answer ⇒ (D)

9. A solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid, the current will

[ A ] Increase

[ B ] Decrease

[ C ] Remain same

[ D ] First increase then decrease

Answer ⇒ (B)

10. There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then

[ A ] current is induced in the loop in the anti-clockwise direction

[ B ] current is induced in the loop in the clockwise direction

[ C ] ac is induced in the loop

[ D ] no current is induced in the loop

Answer ⇒ (A)

7. Alternating Current Test

OBJECTIVE QUESTIONS

1. Alternating currents can be produced by a

[ A ] dynamo

[ B ] choke coil

[ C ] transformer

[ D ] electric motor

Answer ⇒ (A)

2. The alternating current can be measured with the help of

[ A ] hot wire ammeter

[ B ] hot wire voltmeter

[ C ] moving magnet galvanometer

[ D ] suspended coil type galvanometer

Answer ⇒ (A)

3. In which of the following circuits the maximum power dissipation is observed?

[ A ] Pure capacitive circuit

[ B ] Pure inductive circuit

[ C ] Pure resistive circuit

[ D ] None of these

Answer ⇒ (C)

4. With increase in frequency of an A.C. supply, the inductive reactance

[ A ] decreases

[ B ] increases directly with frequency

[ C ] increases as square of frequency

[ D ] decreases inversely with frequency

Answer ⇒ (B)

5. A capacitor acts as an infinite resistance for

[ A ] DC

[ B ] AC

[ C ] DC as well as AC

[ D ] neither AC nor DC

Answer ⇒ (A)

6. The capacitive reactance in an A.C. circuit is

[ A ] effective resistance due to capacity

[ B ] effective wattage

[ C ] effective voltage

[ D ] None of these

Answer ⇒ (A)

7. In LCR circuit if resistance increases quality factor

[ A ] increases finitely

[ B ] decreases finitely

[ C ] remains constant

[ D ] None of these

Answer ⇒ (B)

8. In an L.C.R. series a.c. circuit, the current

[ A ] is always in phase with the voltage

[ B ] always lags the generator voltage

[ C ] always leads the generator voltage

[ D ] None of these

Answer ⇒ (D)

9. At resonance frequency the impedance in series LCR circuit is

[ A ] maximum

[ B ] minimum

[ C ] zero

[ D ] infinity

Answer ⇒ (B)

10. At resonant frequency the current amplitude in series LCR circuit is

[ A ] maximum

[ B ] minimum

[ C ] zero

[ D ] infinity

Answer ⇒ (A)

8. Electromagnetic Waves Test

OBJECTIVE QUESTIONS

1. The electromagnetic waves with frequencies greater than TV signals and less than infrared waves, are called

[ A ] Microwaves

[ B ] X-rays

[ C ] Gamma rays

[ D ] None of these

Answer ⇒ (D)

2. Which of the following help us for recognition of precious stones?

[ A ] Ultraviolet rays

[ B ] Infrared

[ C ] X-rays

[ D ] None

Answer ⇒ (C)

3. Electromagnetic waves are produced by

[ A ] An accelerated charge

[ B ] A charge at rest

[ C ] Uncharged particles

[ D ] Uniformly moving charge

Answer ⇒ (A)

4. Microwaves are of frequency in the range of

[ A ] Micro hertz

[ B ] Mega hertz

[ C ] Giga hertz

[ D ] Hertz

Answer ⇒ (C)

5. Accelerated charges produce

[ A ] Alpha rays

[ B ] Gamma rays

[ C ] Bita rays

[ D ] Electromagnetic wave

Answer ⇒ (D)

6. Which of the following has the lowest wavelength in the electromagnetic spectrum?

[ A ] Microwaves

[ B ] Ultraviolet waves

[ C ] X-rays

[ D ] Gamma rays

Answer ⇒ (D)

7. Electromagnetic wave in free space is

[ A ] Longitudinal

[ B ] Transverse

[ C ] Progressive

[ D ] None of these

Answer ⇒ (B)

8. Maxwell in his famous equations of electromagnetism introduced the concept of

[ A ] ac current

[ B ] displacement current

[ C ] impedance

[ D ] reactance

Answer ⇒ (B)

9. The propagation of electromagnetic wave is along

[ A ] Normal to electric field only

[ B ] Normal to magnetic field only

[ C ] Normal to both the electric and magnetic field

[ D ] None of these

Answer ⇒ (C)

10. Which is a wrong statement?

[ A ] Electromagnetic waves are transverse

[ B ] Electromagnetic waves travel in a vacuum at the speed of light

[ C ] The speed of electromagnetic wave is the same in all media

[ D ] None of these

Answer ⇒ (C)

9. Ray Optics and Optical Instruments Test

OBJECTIVE QUESTIONS

1. Which of the following is not a property of light?

[ A ] It can travel through vacuum

[ B ] It has a finite speed

[ C ] It requires a material medium for its propagation

[ D ] It involve transportation energy

Answer ⇒ (C)

2. Two points P and Q are situated at the same distance from a source of light but on opposite sides. The plane difference between the light waves passing through P and Q will be

[ A ] n

[ B ] 2n

[ C ] π/2

[ D ] zero

Answer ⇒ (D)

3. The phase difference between the electric and the magnetic field vectors in electromagnetic waves is

[ A ] π/4

[ B ] π/2

[ C ] π

[ D ] zero

Answer ⇒ (D)

4. A ray of light traveling in air is incident of a glass slab. The ray gets partly reflected and partly refracted. The phase difference between the reflected and the refracted waves is

[ A ] π/2

[ B ] π/4

[ C ] π

[ D ] zero

Answer ⇒ (C)

5. Which of the following cannot be polarized?

[ A ] radio waves

[ B ] transverse waves

[ C ] sound waves

[ D ] X-rays

Answer ⇒ (C)

6. Light year is the unit of:

[ A ] distance

[ B ] time

[ C ] intensity of light

[ D ] None of these

Answer ⇒ (A)

7. Mirage is a phenomenon due to

[ A ] refraction of light

[ B ] reflection of light

[ C ] total internal reflection of light

[ D ] diffraction of light

Answer ⇒ (C)

8. The refractive indices (R.I.) of glass and water with respect to air are 3/2 and 4/3 respectively. The R.I. of glass w.r. to water is:

[ A ] 8/9

[ B ] 9/8

[ C ] 7/6

[ D ] 2

Answer ⇒ (B)

9. A blue cross on the white background is illuminated with white light and is observed through a red filter. What is seen?

[ A ] A red cross on a black background

[ B ] A blue cross on a red background

[ C ] A red cross on a blue background

[ D ] A black cross on a red background

Answer ⇒ (D)

10. The angle of deviation for a prism is greatest for

[ A ] violet

[ B ] red

[ C ] orange

[ D ] yellow

Answer ⇒ (A)

10. Wave Optics Test

OBJECTIVE QUESTIONS

1. In Young’s double slit experiment, if the monochromatic source of yellow light is replaced by red light, the fringe width

[ A ] increases

[ B ] decreases

[ C ] remains unchanged.

[ D ] the fringes disappear

Answer ⇒ (A)

2. The phenomena which is not explained by Huygen’s construction of wave front

[ A ] reflection

[ B ] diffraction

[ C ] refraction

[ D ] origin of spectra

Answer ⇒ (D)

3. A laser beam is used for locating distant objects because

[ A ] it is monochromatic

[ B ] it is not chromatic

[ C ] it is not observed

[ D ] it has small angular spread.

Answer ⇒ (D)

4. The idea of secondary wavelets for the propagation of a wave was first given by

[ A ] Newton

[ B ] Huygens

[ C ] Maxwell

[ D ] Fresnel

Answer ⇒ (B)

5. When interference of light takes place

[ A ] energy is created in the region of maximum intensity

[ B ] energy is destroyed in the region of maximum intensity

[ C ] conservation of energy holds good and energy is redistributed

[ D ] conservation of energy does not hold good

Answer ⇒ (C)

6. In a double slit interference pattern, the first maxima for infrared light would be

[ A ] at the same place as the first maxima for green light

[ B ] closer to the centre than the first maxima for green light

[ C ] farther from the centre than the first maxima for green light

[ D ] infrared light does not produce an interference pattern

Answer ⇒ (C)

7. Which of the following is correct for light diverging from a point source?

[ A ] The intensity decreases in proportion with the distance squared

[ B ] The wavefront is parabolic

[ C ] The intensity at the wavelength does not depend on the distance

[ D ] None of these.

Answer ⇒ (A)

8. An optically active compound

[ A ] rotates the plane of polarized light

[ B ] changes the direction of polarized light

[ C ] does not allow plane polarized light to pass through

[ D ] none of these

Answer ⇒ (A)

9. Light propagates rectilinearly, due to

[ A ] wave nature

[ B ] wavelengths

[ C ] velocity

[ D ] frequency

Answer ⇒ (A)

10. What is the reason for your answer to the above question?

[ A ] The two sources do not emit light of the same wavelength

[ B ] The two sources emit waves which travel with different speeds

[ C ] The two sources emit light waves of different amplitudes

[ D ] There is not constant phase difference between the waves emitted by the two sources

Answer ⇒ (D)

11. Dual Nature of Radiation and Matter Test

OBJECTIVE QUESTIONS

1. Which phenomenon best supports the theory that matter has a wave nature?

[ A ] Electron momentum

[ B ] Electron diffraction

[ C ] Photon momentum

[ D ] Photon diffraction

Answer ⇒ (B)

2. The photoelectric effect can be explained by

[ A ] Corpuscular theory of light

[ B ] Wave nature of light

[ C ] Bohr’s theory

[ D ] Quantum theory of light

Answer ⇒ (D)

3. Work function of metal is

[ A ] the minimum energy required to free an electron from surface against coulomb forces

[ B ] the minimum energy required to free an nucleon

[ C ] the minimum energy to ionise an atom

[ D ] the minimum energy required to eject an electron orbit

Answer ⇒ (A)

4. Photoelectric effect is based on the law of conservation of

[ A ] energy

[ B ] mass

[ C ] linear momentum

[ D ] angular momentum

Answer ⇒ (A)

5. In photoelectric effect, the number of photoelectrons emitted is proportional to

[ A ] intensity of incident beam

[ B ] frequency of incident beam

[ C ] velocity of the incident beam

[ D ] work function of photocathode

Answer ⇒ (A)

6. Which of the following shows the particle nature of light?

[ A ] Photoelectric effect

[ B ] Refraction

[ C ] Interference

[ D ] Polarization

Answer ⇒ (A)

7. De-Broglie equation states the

[ A ] dual nature

[ B ] particle nature

[ C ] wave nature

[ D ] none of these

Answer ⇒ (A)

8. Protons and alpha particles have the same de-Broglie wavelength. What is the same for both of them ?

[ A ] Energy

[ B ] Time period

[ C ] Frequency

[ D ] Momentum

Answer ⇒ (D)

9. Kinetic energy of emitted electrons depends upon

[ A ] frequency

[ B ] intensity

[ C ] nature of atmosphere surrounding the electrons

[ D ] none of these

Answer ⇒ (A)

10. The ratio of specific charge of an alpha particle to the proton is:

[ A ] 1 : 2

[ B ] 2 : 1

[ C ] 4 : 1

[ D ] 1 : 4

Answer ⇒ (A)

12. Atoms Test

OBJECTIVE QUESTIONS

1. The electrons in the Bohr’s orbit have

[ A ] K.E. greater than P.E.

[ B ] P.E. greater than K.E.

[ C ] the same values

[ D ] none of these

Answer ⇒ (A)

2. The hydrogen atom can give spectral lines in the Lyman, Balmer and Paschen series. Which of the following statements is correct?

[ A ] Lyman series is in the infrared region

[ B ] Balmer series is in the visible region

[ C ] Paschen series is in the visible region

[ D ] Balmer series is in the ultraviolet region

Answer ⇒ (A)

3. In Bohr’s model of an atom which of the following is an integral multiple of h/2π?

[ A ] Kinetic energy

[ B ] Radius of an atom

[ C ] Potential energy

[ D ] Angular momentum

Answer ⇒ (D)

4. Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is

[ A ] 10.20 eV

[ B ] 20.40 eV

[ C ] 13.6 eV

[ D ] 27.2 eV

Answer ⇒ (A)

5. The ratio between Bohr radii is

[ A ] 1 : 2 : 3

[ B ] 2 : 4 : 6

[ C ] 1 : 4 : 9

[ D ] 1 : 3 : 5

Answer ⇒ (C)

6. For ionizing an excited hydrogen atom, the energy required (in eV) will be

[ A ] a little less than 13.6 eV

[ B ] 13.6 eV

[ C ] more than 13.6 eV

[ D ] 3.4 or less

Answer ⇒ (D)

7. In terms of Rydberg constant R, the wave number of the first Balmer line is

[ A ] R

[ B ] 3R

[ C ] 5R/36

[ D ] 8R/9

Answer ⇒ (C)

8. The ionization energy of a hydrogen atom is 13.6 eV. Following Bohr’s theory the energy corresponding to a transition between 3rd and 4th orbits is

[ A ] 3.40 Ev

[ B ] 1.51 eV

[ C ] 0.85 eV

[ D ] 0.66 eV

Answer ⇒ (D)

9. The electrons in the Bohr’s orbit have

[ A ] K.E greater than P.E

[ B ] P.E greater than K.E

[ C ] the same values

[ D ] none of these

Answer ⇒ (A)

10. On moving up in the energy states of a H-like atom, the energy difference between two consecutive energy states

[ A ] Decreases

[ B ] Increases

[ C ] First decreases then increases

[ D ] First increases then decreases

Answer ⇒ (A)

13 Nuclei Test

OBJECTIVE QUESTIONS

1. Heavy stable nuclei have more neutrons than protons. This is because of the fact that

[ A ] Neutrons are heavier than protons

[ B ] Electrostatic force between protons are repulsive

[ C ] Neutrons decay into protons through beta decay

[ D ] Nuclear forces between neutrons are weaker than that between protons

Answer ⇒ (B)

2. Radioactivity is the phenomenon associated with

[ A ] Decay of nucleus

[ B ] Production of radio waves

[ C ] Transmission of radio waves

[ D ] Reception of radio waves

Answer ⇒ (A)

3. Which of the following are not emitted by radioactive substances?

[ A ] Electrons

[ B ] Protons

[ C ] Gamma rays

[ D ] Helium nuclei

Answer ⇒ (B)

4. In an α-decay

[ A ] The parent and daughter nuclei have some number of protons

[ B ] The daughter nucleus has one proton more than the parent nucleus

[ C ] The daughter nucleus has two protons less than the parent nucleus

[ D ] The daughter nucleus has two more than the parent nucleus.

Answer ⇒ (C)

5. When a radioactive nucleus emits a (β-particle, the mass number of the atom:

[ A ] Increases by one

[ B ] Remains the same

[ C ] Decreases by one

[ D ] Decreases by four

Answer ⇒ (B)

6. In a β-decay

[ A ] The parent and daughter nuclei have the same number of protons

[ B ] The daughter nucleus has one proton less than the parent nucleus

[ C ] The daughter nucleus has one proton more than the parent nucleus

[ D ] The daughter nucleus has one neutron more than the parent nucleus

Answer ⇒ (C)

7. P-rays emitted by a radioactive material are

[ A ] Electromagnetic radiation.

[ B ] Electrons orbiting around the nucleus.

[ C ] Neutral particles

[ D ] Charged particles emitted by the nucleus

Answer ⇒ (D)

8. γ-rays are originated from

[ A ] nucleus

[ B ] Outermost shell of nucleus

[ C ] Innermost shell of nucleus

[ D ] Outermost shell of atom

Answer ⇒ (A)

9. Binding energy per nucleon of a stable nucleus is

[ A ] 8 eV

[ B ] 8 KeV

[ C ] 8 MeV

[ D ] 8 BeV

Answer ⇒ (C)

10. Sun’s radiant energy is due to

[ A ] Nuclear fission

[ B ] Nuclear fusion

[ C ] Photoelectric effect

[ D ] Spontaneous radioactive decay

Answer ⇒ (B)

14. Semiconductor Electronic Test

OBJECTIVE QUESTIONS

1. Crystal diode is

[ A ] amplifying device

[ B ] fluctuating device

[ C ] non-linear device

[ D ] linear device

Answer ⇒ (C)

2. In a full wave rectifier, input a.c. current has a frequency v. The output frequency of current is

[ A ] V/2

[ B ] V

[ C ] 2V

[ D ] None

Answer ⇒ (A)

3. Which of the following gate not a universal gate?

[ A ] OR

[ B ] NOT

[ C ] AND

[ D ] NAND

Answer ⇒ (D)

4. Zener diode is used for

[ A ] producing oscillations in a oscillator

[ B ] amplification

[ C ] stabilization

[ D ] rectification

Answer ⇒ (C)

5. In semiconductor, at room temperature

[ A ] the valence bond is partially empty and the conduction band is partially filled

[ B ] the valence band is completely filled and the conduction band is partially filled

[ C ] the valence band is completely filled

[ D ] the conduction band is completely empty

Answer ⇒ (A)

6. In semiconductor which are responsible for conduction

[ A ] only electron

[ B ] electron and hole both

[ C ] only hole

[ D ] None of these

Answer ⇒ (B)

7. The part of a transistor which is heavily doped to produce a large number of majority carriers is

[ A ] base

[ B ] emitter

[ C ] collector

[ D ] None of these

Answer ⇒ (B)

8. p-n junction diode can be used as:

[ A ] amplifier

[ B ] oscillator

[ C ] detector

[ D ] modulator

Answer ⇒ (C)

9. In intrinsic semiconductor at room temperature, the number of electrons and holes are:

[ A ] equal

[ B ] unequal

[ C ] infinite

[ D ] zero

Answer ⇒ (A)

10. The part of the transistor which is heavily doped to produce a large number of majority carriers is

[ A ] emitter

[ B ] base

[ C ] collector

[ D ] none

Answer ⇒ (A)

15. Communication Systems Test

OBJECTIVE QUESTIONS

1. The output of a digital computer is an example of

[ A ] digital signal

[ B ] analog signal

[ C ] both a and b

[ D ] neither a nor b

Answer ⇒ (A)

2. In amplitude modulation

[ A ] the amplitude of the carrier remains constant

[ B ] the amplitude of the carrier varies in accordance with the amplitude of the modulating signal

[ C ] the amplitude of the carrier varies in accordance with the frequency of the modulating signal

[ D ] None of these

Answer ⇒ (B)

3. In modulation process, radio frequency wave is termed as

[ A ] modulating wave

[ B ] modulated wave

[ C ] carrier wave

[ D ] none

Answer ⇒ (C)

4. Digital signals

[ A ] represent values as discrete steps

[ B ] utilize binary code system

[ C ] do not provide a continuous set of values

[ D ] All of these

Answer ⇒ (D)

5. Modulation index in an FM signal:

[ A ] Varies directly as the modulating frequency

[ B ] Varies directly as frequency deviation and inversely as the modulating frequency

[ C ] varies inversely as the frequency deviation

[ D ] None of these.

Answer ⇒ (B)

6. The most commonly employed analog modulation technique in satellite communication is the

[ A ] amplitude modulation

[ B ] frequency modulation

[ C ] phase modulation

[ D ] All of the above.

Answer ⇒ (B)

7. AM is used for broadcasting because

[ A ] it is more noise immune than other modulation system

[ B ] it requires less transmitting power compare with other systems

[ C ] its use avoids receiver complexity

[ D ] No other modulation system can provide the necessary bandwidth faithful transmission

Answer ⇒ (C)

8. For television transmission, the frequency employed is normally in the range

[ A ] 30-300 Hz

[ B ] 30-300 kHz

[ C ] 30-300 MHz

[ D ] 30-300 GHz

Answer ⇒ (C)

9. Which one of the following can happen to the electromagnetic waves traveling in free space

[ A ] Reflection

[ B ] Refraction

[ C ] absorption

[ D ] attenuation

Answer ⇒ (D)

10. High frequency waves are

[ A ] reflected by the E layer

[ B ] absorbed by the F layer

[ C ] affected by the solar cycle

[ D ] capable of use for long-distance transmission

Answer ⇒ (A)