Current Electricity — Physics STD 12 Science — Question

A 100 turns coil shown in figure carries a current of 2 amp in a magnetic field . The torque acting on the coil is

(a) 0.32 Nm tending to rotate the side AD out of the page

(b) 0.32 Nm tending to rotate the side AD into the page

(c) 0.0032 Nm tending to rotate the side AD out of the page

(d) 0.0032 Nm tending to rotate the side AD into the page

The frequencies of X-rays, g-rays and ultraviolet rays are respectively a, b and c. Then

(a) a < b, b > c

(b) a > b, b > c

(c) a > b, b < c

(d) a < b, b < c

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency of the incident radiation gives as straight the whose slope?

In hydrogen atom, the electron makes 6.6   revolutions per second around the nucleus in an orbit of radius 0.5 . It is equivalent to a current nearly

(a) 1 A

(b) 1 mA

(c) 1 μA

(d) 1.6

Moving charge produces:

The potential energy of a particle of mass m is given by

U(x) =

l₁ and l₂ are the de-Broglie wavelengths of the particle, when 0 £ x £ 1 and x > 1 respectively. If the total energy of particle is 2E₀, the ratio    will be

(a) 2

(b) 1

(c)

(d)

The property between two charged ebonite rods is:

In a transformer, number of turns in the primary are 140 and that in the secondary are 280. If current in primary is 4A then that in the secondary is

(a) 4 A

(b) 2 A

(c) 6 A

(d) 10 A

In human eye the focussing is done by

(a) To and fro movement of eye lens

(b) To and fro movement of the retina

(c) Change in the convexity of the lens surface

(d) Change in the refractive index of the eye fluids

If the threshold wavelength for sodium is 5420 Å, then the work function of sodium is

(a) 4.58 eV

(b) 2.28 eV

(c) 1.14 eV

(d) 0.23 eV