MATRIC • FSC • NTS • ETEA • CSS • PMS etc MCQs Learn, Practice, Prepare, Succeed! Prepare Today, Succeed Tomorrow!

Q: The diode that converts electrical energy into light energy is called (ET 2012)

A) Solar cell

B) Photo diode

C) Vacuum diode

D) Light emitting diode

Q: The ratio of output voltage Vo to the voltage difference Vin between positive and negative input of op-amp is (ET 2012)

A) current gain

B) voltage gain

C) open-loop gain

D) close-loop gain

Q: Operational amplifiers can amplify (ET 2014)

A) ac only

B) dc only

C) both ac and dc

D) none of them

Q: In Compton scattering from stationary electrons the largest change in wavelength occurs when the photon is scattered through (ET 2016)

A) 0°

B) 45°

C) 90°

D) 180°

Q: Which property of an electron is used in the electron microscope? (ET 2016)

A) High velocity

B) Wave nature

C) Interference

D) Diffraction

Q: The number of photoelectrons emitted per second from the metal surface depends upon (Entry Test 2007)

A) Intensity of light

B) Frequency of light

C) wavelength of light

D) speed of light

Q: Three metals cesium, potassium, tungsten are illuminated by same frequency light. Which emits photoelectrons of greatest K.E.? (Entry Test 2009)

A) Cesium

B) Potassium

C) Tungsten

D) None

Q: If the frequency of incident light beam is doubled, the kinetic energy of the emitted photoelectron is (ET 2009)

A) Doubled

B) More than doubled

C) Unchanged

D) Less than doubled

Q: The rest mass energy of electron is (Entry Test 2010)

A) 0.51 Joule

B) 1.02 Joule

C) 9.11×10⁻³¹ Joule

D) 8.2×10⁻¹⁴ Joule

Q: The best shield against X-rays is (Entry Test 2010)

A) Lead

B) Steel

C) Iron

D) Copper

Q: The wave nature of an electron is illustrated by its (Entry Test 2011-2015)

A) Photoelectric effect

B) Compton effect

C) Penetrating effect

D) Diffraction

Q: The scattering angle θ for which Compton shift is equal to Compton wavelength is (Entry Test 2011/2016)

A) 0°

B) 45°

C) 90°

D) 180°

Q: The uncertainty in energy of photon emitted from an atom radiating for 10⁻⁸ s is (Entry Test 2011-2014)

A) 4×10⁻⁷ J

B) 4×10 eV

C) 6.6×10⁻² eV

D) 4×10⁷

Q: If the temperature of the blackbody becomes doubled, the intensity of radiation becomes (Entry Test 2011)

A) Doubled

B) Four times

C) Six times

D) Sixteen times

Q: If intensity of monochromatic beam of light is doubled, the momentum of each photon becomes (ET 2016)

A) Increased

B) Double

C) Same

D) Halved

Q: The work function of a metal is 6.63 eV. Its threshold frequency is (ET 2012)

A) 1.6×10¹⁵ Hz

B) 1.6×10¹² Hz

C) 6.63×10¹ Hz

D) 1.6×10⁻¹⁰ Hz

Q: Which electromagnetic radiation has photons with the greatest momentum? (ET 2015)

A) Blue light

B) Yellow light

C) X-rays

D) Radio waves

Q: If 50 kV is the applied potential in an X-ray tube, the minimum wavelength of X-rays produced is (ET 2016)

A) 0.2 nm

B) 2 nm

C) 0.02 nm

D) 2 Å

Q: The energy of electron in the 1st orbit is (ET 2016)

A) -13.6×10⁻¹⁹ J

B) -3.4×10⁻¹⁸ J

C) -2.17×10⁻¹⁸ J

D) 1.5×10⁻¹⁹ J

Q: The energy of electron in excited state n=4 in Hydrogen atom is (ET 2010)

A) -13.6 eV

B) -3.4 eV

C) -0.85 eV

D) -1.5 eV