# Gr Xii Physics- Part-2 Revision 2

15 Questions | Total Attempts: 70  Settings  Mixed Questions from Ray Optics, Wave Optics , Dual Nature

• 1.
What is path difference for destructive interference?
• A.

(a) nλ

• B.

(b) n(λ +1)

• C.

(c) (2n + 1)λ/2

• D.

(d) (n +1)λ/ 2

• 2.
When exposed to sunlight, thin films of oil on water of ten exhibit brilliant colours due to the phenomenon of
• A.

Interference

• B.

Diffraction

• C.

Dispersion

• D.

Refraction

• 3.
What happens, if the monochromatic light used in Young’s double slit experiment is replaced by white light?
• A.

(a) No fringes are observed.

• B.

(b) All bright fringes become while.

• C.

(c) All bright fringes have colour between violet and red.

• D.

(d) Only the central fringe is white and all other fringes are coloured.

• 4.
The phenomenon of interference is based on
• A.

(a) conservation of momentum.

• B.

(b) conservation of energy.

• C.

(c) conservation of momentum and energy.

• D.

(d) quantum nature of light.

• 5.
A double slit interference experiment is carried out in air and the entire arrangement is dipped in water. The fringe width
• A.

(a) increases

• B.

(b) decreases

• C.

(c) remains unchanged.

• D.

(d) fringe pattern disappears.

• 6.
A double convex lens of refractive index µ1 is immersed in a liquid of refractive index µ2. The lens will act as transparent plane sheet when
• A.

(a) µ1 = µ2

• B.

(b) µ1 > µ2

• C.

(c) µ1 < µ2

• D.

(d) µ1 = 1/ μ2

• 7.
When a ray of light enters from one medium to another, then which of the following does not change?
• A.

Frequency

• B.

Wavelength

• C.

Speed

• D.

Amplitude

• 8.
Mirage is a phenomenon due to
• A.

Refraction of light

• B.

Reflection of light

• C.

Total internal reflection of light

• D.

Diffraction of light

• 9.
A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
• A.

Become zero

• B.

Become infinite

• C.

Become small, but non-zero

• D.

Remain unchanged

• 10.
Two beams of red and violet color are made to pass separately through a prism (angle of the prism is 60°). In the position of minimum deviation, the angle of refraction will be
• A.

(a) 30° for both the colors

• B.

(b) greater for the violet color

• C.

(c) greater for the red color

• D.

(d) equal but not 30° for both the colors

• 11.
In photoelectric effect, the maximum velocity of the emitted electron depends on
• A.

(a) Intensity of the incident light

• B.

(b) Frequency of the incident light

• C.

(c) threshold frequency

• D.

(d) Both (b) and (c) above

• 12.
Two metals A and B have work function 2eV and 4 eV respectively .which metal has a lower threshold wavelength for the photoelectric effect?
• A.

(a) A

• B.

(b) B

• C.

(c) same for both

• D.

(d) cannot say

• 13.
An electron and proton have the same De Broglie wavelength . Which one of these has the higher kinetic energy?. Which one is moving faster?
• A.

Electron has higher K.E and it will move faster

• B.

Proton has higher K.E and it will move faster

• C.

Both will have same kinetic energy, but proton will move faster.

• D.

Both will have same kinetic energy, but electron will move faster.

• 14.
Which one do you like?
• A.

(a) a -> p, b -> q , c -> r.

• B.

(b) a -> r, b -> q , c -> p.

• C.

(c) a -> r, b -> p , c -> q.

• D.

(d) a -> p, b -> r , c -> q.

• 15.
The de Broglie wavelength of an electron accelerated to a potential of 400 V is approximately
• A.

(a) 0.03 nm

• B.

(b) 0.04 nm

• C.

(c) 0.12 nm

• D.

(d) 0.06 nm Back to top