All Free Physics MCQs with Answers

• A. Spectrometer
• B. Telescope
• C. Microscope
• D. Interferometer

Explanation: A spectrometer is an instrument used to measure the properties of light over a specific portion of the electromagnetic spectrum.

• A. wavelength of light
• B. speed of light
• C. frequency of light
• D. Both A and B

Explanation: Both the wavelength and speed of light change when light passes from air to glass.

• A. 180°
• B. 120°
• C. 90°
• D. 0°

Explanation: When a light wave passes from a rarer medium to a denser medium, there will be a phase change of 180°.

• A. 0.5
• B. 10
• C. 20
• D. 0.05

Explanation: Magnifying power of telescope = focal length of objective/focal length of eyepiece = power of eyepiece/ power of objective Power of…

• A. Interference
• B. Polarization
• C. Diffraction
• D. Dispersion

Explanation: The phenomenon of polarization is used to verify the transverse nature of light.

• A. Current
• B. Light
• C. Sound
• D. Voltage

Explanation: Optical fibers are designed to guide light, which is used for transmitting data over long distances with minimal loss.

• A. 250
• B. 500
• C. 1000
• D. 4000

Explanation: To solve this problem, we use the formula for diffraction grating: d sin(θ) = nλ, where d is the grating spacing, θ is the angle of…

• A. Polarized
• B. Refracted
• C. Reflected
• D. Diffracted

Explanation: Light waves can be polarised but sound waves cannot.

• A. Dispersion
• B. Interference of light
• C. Absorption of light
• D. Scattering of light

Explanation: Multiple colors are observed on the oil floating on water due to the phenomenon of interference.

• A. Highly coherent
• B. Plane polarized
• C. Intense
• D. Highly directional

Explanation: A laser beam is sharply focused primarily because it is highly directional.

• A. The slit width should be increased
• B. The slit width should be decreased
• C. The slit separation should be increased
• D. The slit separation should be decreased

Explanation: The correct answer is to decrease the slit separation. In a diffraction grating, narrower slit separation results in larger angular…

• A. Its wave length decreases
• B. Its wave length in creases
• C. Its frequency increases
• D. Its frequency decreases

Explanation: As the medium is dense, the speed decreases. The frequency has to remain constant therefore the wavelength decreases ( v = fλ)

• A. 3
• B. 4
• C. 5
• D. 1

Explanation: Explanation is given below.The formula for the number of images formed by a diffraction grating is:nλ = d(sinθ + sinφ)where n is the order…

• A. Reflection of light
• B. Division of wavelenght
• C. Refraction of light
• D. Division of amplitude

Explanation: The principle of thin film interference is based on the division of wavelengths of light.

• A. Critical angle
• B. At any angle, both rays are perpendicular
• C. Brewster's angle
• D. Inclination angle

Explanation: Brewster's angle is the angle of incidence at which the reflected and refracted rays are perpendicular to each other.

• A. Equal to 1
• B. Equal to 2L
• C. Equal to 4L
• D. Equal to 3l/2

Explanation: Equal to 2L: This option is correct. In an open organ pipe, the fundamental wavelength corresponds to the length of the pipe, so the…

• A. 2m
• B. 4m
• C. 6m
• D. 8m

Explanation: For an open pipe at both ends, the fundamental frequency is given by: f = v/2LWhere v is the speed of sound and L is the length of the…

• A. 4 × T
• B. 2 × T
• C. 3 × T
• D. 1 × T

Explanation: The fundamental mode of a closed-open organ pipe produces a wavelength that is four times the length of the pipe.

• A. Maximum
• B. Zero
• C. Maximum and minimum
• D. No change in emf

Explanation: Zero: The mean value of a sinusoidal emf over a cycle is zero. This is because the positive and negative values of the sinusoidal wave…

• A. Zero
• B. Constant
• C. Positive
• D. Maximum

Explanation: The average current value in a complete cycle of AC waveform, such as a sine wave, is zero because the positive and negative parts of the…