Electric Charges and Fields — Physics STD 12 Science — Question

The wavelength of sodium light in air is 5890 Å. The velocity of light in air is 3  The wavelength of light in a glass of refractive index 1.6 would be close to

(a) 5890 Å

(b) 3681 Å

(c) 9424 Å

(d) 15078 Å

A short magnet oscillates with a time period 0.1 s at a place where horizontal magnetic field is 24μT. A downward current of 18 A is established in a vertical wire 20 cm east of the magnet. The new time period of oscillator

(a) 0.1 s

(b) 0.089 s

(c) 0.076 s

(d) 0.057 s

In Young's double slit experiment, the phase difference between the light waves reaching third bright fringe from the central fringe will be (λ =6000 Å )

(a) Zero

(b) 2π

(c) 4 π

(d) 6 π

A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a

(a) Convex mirror of focal length 10 cm

(b) Concave mirror of focal length 40 cm

(c) Concave mirror of focal length 60 cm

(d) Concave mirror of focal length 10 cm

Einstein was awarded a Noble Prize for:

Two photons, each of energy 2.5 eV are simultaneously incident on the metal surface. If the work function of the metal is 4.5 eV, then from the surface of the metal:

The resistance of a wire is   per metre. It is bend in the form of a circle of diameter 2 m. A wire of the same material is connected across its diameter. The total resistance across its diameter AB will be

(a)

(b)

(c) 0.88

(d) 14π

Which of the following parameters is the same for molecules of all gases at a given temperature?

1. Mass.
2. Speed.
3. Momentum.
4. Kinetic energy.

When a thin transparent plate of thickness t and refractive index m is placed in the path of one of the two interfering waves of light, then the path difference changes by

(a) (m + 1)t

(b) (m – 1)t

(c)

(d)