Assertion & Reason Test: Wave Optics - ACT MCQ

Directions : In the following questions, A statement of Assertion(A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): According to Huygens theory no back-ward wavefront is possible.

Reason (R): Amplitude of secondary wavelets is proportional to (1+ cos q), where q is the angle between the ray at the point of consideration and direction of secondary wavelet.

Directions : In the following questions, A statement of Assertion(A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): When a light wave travels from rarer to denser medium, its speed decreases. Due to this reduction of speed the energy carried by the light wave reduces.

Reason (R): Energy of the wave is proportional to the frequency.

Directions : In the following questions, A statement of Assertion(A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): For best contrast between maxima and minima in the interference pattern of Young’s double slit experiment, the amplitudes of light waves emerging from the two sources should be equal.

Reason (R): For interference, the sources must be coherent.

Directions : In the following questions, A statement of Assertion(A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Diffraction takes place with all types of waves.

Reason (R): Diffraction is perceptible when the wavelength of the wave is comparable to the dimension of the diffracting device.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Thin film such as soap bubbles or a thin layer of oil on water show beautiful colours when illuminated by white light.

Reason : It happens due to the interference of light reflected from the upper and lower face of the thin film.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : It is necessary to have two waves of equal intensity to study interference patterns.

Reason : There will be an effect on clarity if the waves are of unequal intensity.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : In YDSE, if a thin film is introduced in front of the upper slit, then the fringe pattern shifts in the downward direction.

Reason : In YDSE if the slit widths are unequal, the minima will be completely dark.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : In YDSE number of bright fringe or dark fringe can not be unlimited

Reason : In YDSE path difference between the superposing waves can not be more than the distance between the slits.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Coloured spectrum is seen when we look through a muslin cloth.

Reason : It is due to the diffraction of white light on passing through fine slits.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : According to Huygen’s principle, no backward wave-front is possible.

Reason : Amplitude of secondary wavelet is proportional to (1 + cos θ) where θ is the angle between the ray at the point of consideration and the direction of secondary wavelet.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : No interference pattern is detected when two coherent sources are infinitely close to each other.

Reason : The fringe width is inversely proportional to the distance between the two sources.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : White light falls on a double slit with one slit is covered by a green filter. The bright fringes observed are of green colour.

Reason : The fringes observed are coloured.

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : In Young’s double slit experiment if wavelength of incident monochromatic light is just doubled, the number of bright fringes on the screen will increase.

Reason : Maximum number of bright fringe on the screen is inversely proportional to the wavelength of light used

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Interference pattern is made by using yellow light instead of red light, the fringes become narrower.

Reason : In YDSE, fringe width is given by β=λD/d

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Diffraction takes place for all types of waves mechanical or nonmechanical, transverse or longitudinal.

Reason : Diffraction’s effects are perceptible only if wavelength of wave is comparable to dimensions of diffracting device.