Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Carbon dating is best suited for determining the age of fossils if their age in years is of the order of

(a)

(b)

(c)

(d)

The electric field near a conducting surface having a uniform surface charge density σ  is given by

(a)  and is parallel to the surface	(b)  and is parallel to the surface
(c)  and is normal to the surface	(d)  and is normal to the surface

A beam of light is converging towards a point I on a screen. A plane glass plate whose thickness in the direction of the beam = t, refractive index = μ, is introduced in the path of the beam. The convergence point is shifted by

(a) away

(b)  away

(c)  nearer

(d)  nearer

If the distance between the plates of parallel plate capacitor is halved and the dielectric constant of dielectric is doubled, then its capacity will

(a) Increase by 16 times	(b) Increase by 4 times
(c) Increase by 2 times	(d) Remain the same

The resistance and inductance of series circuit are 5 and 20H respectively. At the instant of closing the switch, the current is increasing at the rate 4A - s. The supply voltage is

(a) 20 V

(b) 80 V

(c) 120 V

(d) 100 V

What is the atomic mass (u) of sodium?

A non.monochromatic light is used in an experiment on photoelectric effect. The stopping potential:

1. Is related to the mean wavelength.
2. Is related to the longest wavelength.
3. Is related to the shortest wavelength.
4. Is not related to the wavelength.

Three charges Q(+q)  and (+q)  are placed at the vertices of an equilateral triangle of side l as shown in the figure. If the net electrostatic energy of the system is zero, then Q is equal to

(a)

(b) (-q)

(c) (+q)

(d) Zero

A convex lens of focal length 12 cm is made of glass of μ = . What will be its focal length when immersed in liquid of μ =  

(a) 6 cm

(b) 12 cm

(c) 24 cm

(d) 30 cm