All Free Physics MCQs with Answers

• A. 100 A
• B. 25 A
• C. 50 A
• D. 20 A

Explanation: The sinusoidal AC current given by the equation I = 50 sin(20t) has a peak value that is determined by the amplitude of the sine function.

• A. 100 Hz
• B. 200Hz
• C. 50 Hz
• D. 150Hz

Explanation: If we compare the given equation with the formula V=Vosin(wt+ϕ),Vo=20, ϕ=0, w=100.

• A. 5A
• B. 2.5A
• C. 5√2 A
• D. 52 A

Explanation: The mean square value (RMS value) of the current is calculated as:RMS value = Peak value / √2= 5√2 / √2= 5 A Therefore, option a is correct.

• A. 150Hz
• B. 50Hz
• C. 100Hz
• D. 200Hz

Explanation: In most countries, the domestic electricity supply, also known as the mains electricity or grid power, has a frequency of 50Hz (50 cycles…

• A. Pair production
• B. Compton effect
• C. Annihilation of matter
• D. photoelectric effect

Explanation: A.The creation of an elementary particle and its antiparticle, usually when a photon (or another neutral boson) interacts with a nucleus…

• A. Intensity of the incident light
• B. Frequency of the incident light
• C. Temperature of the photosensitive surface
• D. None of the above

Explanation: The maximum KE of emitted photoelectrons depends on the frequency of incident lightThis can be represented by the photoelectric equationEk…

• A. Intensity of light
• B. Frequency of light
• C. Wavelength of light
• D. Speed of light

Explanation: According to Planck's quantum theory, the intensity of the incident beam is directly related to the number of photons in the beam.

• A. E = 0.52 Mev
• B. E < 1.02 Mev
• C. E < 0.52 Mev
• D. E > 1.02 Mev

Explanation: Pair production is a process in which a photon interacts with a nucleus or an atomic electron and produces an electron-positron pair.

• A. Doubled
• B. More than double
• C. Unchanged
• D. Less than double

Explanation: More than double: From Einstein's equation for photoelectric effect , the maximum kinetic energy , K=hν−W where ν= frequency of incident…

• A. Max Planck
• B. Compton
• C. Lousie
• D. Einstein

Explanation: Albert Einstein was awarded the Noble Prize in Physics in 1921 for his explanation of the photoelectric effect, which he published in…

• A. 0=90°
• B. 0=0"
• C. 0=45°
• D. 0=180°

Explanation: COMPTON'S EFFECT: It is the scattering of a high-frequency photon after a collision with an electron, which results in a decrease in the…

• A. The photon's frequency only
• B. The metal work function and photon's frequency
• C. The intensity of incident light
• D. None of the above

Explanation: The maximum kinetic energy of an electron ejected from a metal by a photon is calculated using the equation K_max = hf - φ, where h is…

• A. Critical frequency
• B. Threshold frequency
• C. Work function
• D. None of the above

Explanation: This minimum frequency is also called the threshold frequency, and the value of ν0 \nu, start subscript, 0, end subscript depends on the…

• A. v = f.λ
• B. λ = h / mv
• C. s = d/t
• D. p = λ x h

Explanation: The correct formula to calculate the wavelength of an electron is λ = h / mv, known as De Broglie's wave equation.

• A. Blue light
• B. Yellow light
• C. X-rays
• D. Radio wave

Explanation: According to the de Broglie equation, wavelength and momentum are inversely proportional.

• A. 00
• B. 450
• C. 900
• D. 1800

Explanation: The largest change in wavelength occurs when the photon is scattered through 180 degrees because the photon is reflected directly back in…

• A. Increase in intensity of light
• B. Increase in wavelength of light
• C. Increase in frequency of light
• D. Never

Explanation: The correct answer is that the number of ejected photoelectrons increases with an increase in the intensity of light.

• A. Stopping potential
• B. Maximum kinetic energy of Photoelectron
• C. Photoelectric current
• D. Both (A) & (B)

Explanation: If the frequency of the incident radiation in the photoelectric effect is increased beyond the threshold frequency, it will affect the…

• A. The number of photons
• B. The energy of each photon
• C. The speed of the photons
• D. The frequency of photons

Explanation: Einstein proposed the idea that light is quantized into discrete packets of energy called photons.

• A. Compton effect
• B. Photoelectric effect
• C. Pair production
• D. Pair Annihilation

Explanation: Pair production is the process in which a photon interacts with a nucleus and produces an electron-positron pair.