Free MCQs & Online Quiz Practice for Exams

Q: Most of the electrons in the base of an NPN transistor flow:

A) Out of the base lead

B) Into the collector

C) Into the emitter

D) Into the base supply

Q: In a transistor, collector current is controlled by:

A) Collector voltage

B) Base current

C) Collector resistance

D) All of the above

Q: The minimum number of diodes required for full wave rectification are:

A) 3

B) 4

C) 1

D) 2

Q: In a transistor both collector-base and base-emitter junctions are reversed biased then it is:

A) Active region

B) Cutoff region

C) Saturation region

D) Q-point

Q: Triplets A and B board spaceships and head away from Earth in opposite directions, each traveling the same distance at the same speed before returning to Earth. Triplet C remains on Earth. Which expression describes the triplets' relative ages once they're reunited on Earth?

A) A < B < C

B) A = B > C

C) A = B < C

D) A = B = C

Q: If a spaceship travels from Earth to a planet in the Alpha Centauri star system, which observer measures the proper time for the trip?

A) An observer on Earth

B) An observer on the planet in the Alpha Centauri star system

C) An observer on the spaceship

D) An observer deep in space far from the planet and Earth

Q: When you compress a spring between your fingers, its mass:

A) Increases

B) Decreases

C) Stays the same

D) Turns negative

Q: By doubling the absolute temperature of a black body, the total energy radiated will change by a factor of:

A) 0.5

B) 2

C) 4

D) 16

Q: According to Einstein, increasing the brightness of a beam of light without changing its color will increase:

A) The number of photons

B) The energy of each photon

C) The speed of the photons

D) The frequency of the photons

Q: Sources of red, blue, and yellow light each emit light with a power of 50 mW. The source which emits more photons is:

A) Red

B) Blue

C) Yellow

D) They all emit the same number per second

Q: Which of the following energies for photons is the least energy that could result in photoelectron production if the work function is 3.00 eV?

A) 1.50 eV

B) 2.90 eV

C) 3.50 eV

D) 6.01 eV

Q: In a Compton scattering experiment, at which angle does the electron carry maximum energy?

A) 0°

B) 90°

C) 135°

D) 180°

Q: If X-rays are scattered from protons instead of electrons, the change in its wavelength for a given angle of scattering:

A) Increases

B) Decreases

C) Is unchanged

D) Is one radian

Q: Pair production cannot take place in vacuum because:

A) Mass is not conserved

B) Momentum is not conserved

C) Energy is not conserved

D) Charge is not conserved

Q: According to de Broglie equation, which particle has the smallest wavelength?

A) Neutron

B) Proton

C) Alpha particle

D) Electron

Q: In electron microscope, light source is replaced by a beam of very fast moving:

A) Electron

B) Neutron

C) Proton

D) Photon

Q: According to Heisenberg, as the uncertainty in the measurement of a particle's momentum is reduced by a factor of 2, by what factor is the uncertainty in that same particle's position changed?

A) 1/2

B) 1

C) 2

D) 4

Q: Which of the following series of hydrogen spectra lies in the visible region of the spectrum?

A) Lyman

B) Balmer

C) Paschen

D) Brackett

Q: The longest wavelength in Balmer's series has wavelength 656.2 nm. Its transition corresponds to:

A) n=3

B) n=4

C) n=5

D) n=∞

Q: If 13.6 eV energy is required to ionize the hydrogen atom, then the required energy to remove an electron from n=2 is:

A) 3.4 eV

B) 6.8 eV

C) 10.2 eV

D) 0 eV