Nuclei — Physics STD 12 Science — Question

A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index m = 1.5) making an incidence angle of 60^o on the lateral surface, so that it undergoes a total internal reflection.  How much time would it take to traverse the straight fiber of length 1 km

(a) 3.33 m sec

(b) 6.67 m sec

(c) 5.77 m sec

(d) 3.85 m sec

Figure shows a closed surface which intersects a conducting sphere. If a positive charged is placed at the point P, the flux of the electic field through the closed surface:

The energy of emitted photoelectrons depends upon :

If in a nuclear fusion process the masses of the fusing nuclei be  and   and the mass of the resultant nucleus be , then

(a)

(b)

(c)

(d)

Choose the correct statement

(a) When we heat a semiconductor its resistance increases

(b) When we heat a semiconductor its resistance decreases

(c) When we cool a semiconductor to 0 K then it becomes super conductor

(d) Resistance of a semiconductor is independent of temperature

70 calories of heat are required to raise the temperature of 2 mole of an ideal gas at constant pressure from 30° C to 35° C. The amount of heat required to raise the temperature of the same gas through the same range at constant volume is:

1. 30 calories.
2. 50 calories.
3. 70 calories.
4. 90 calories.

If the inductance and capacitance are both doubled in L - C - R circuit, the resonant frequency of the circuit will:

Who first proposed the light as an electromagnetic wave?