Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

For a nucleus to be stable, the correct relation between neutron number N and Proton number Z is

(a) N > Z

(b) N = Z

(c) N < Z

(d) N ≥ Z

A 20F capacitor is charged to 5V and isolated. It is then connected in parallel with an uncharged 30F capacitor. The decrease in the energy of the system will be

(a) 25 J

(b) 200 J

(c) 125 J

(d) 150 J

The number of turns in primary and secondary coils of a transformer are 100 and 20 respectively. If an alternating potential of 200 volt is applied to the primary, the induced potential in secondary will be

(a) 10 V

(b) 40 V

(c) 1000 V

(d) 20,000 V

 A variable condenser is permanently connected to a 100 V battery. If the capacity is changed from 2μF to 10 μF, then change in energy is equal to

(a) 2

(b) 2.5

(c) 3.5

(d) 4

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it:

When an impurity is doped into an intrinsic semiconductor, the conductivity of the semiconductor:

The correct curve between the stopping potential (V) and intensity of incident light (I) is

(a)

(b)

(c)

(d)

When a slab of dielectric material is introduced between the parallel plates of  a capacitor which remains connected to a battery, then charge on  plates relative to earlier charge

(a) Is less

(b) Is same

(c) Is more

(d) May be less or more depending on the nature of the material introduced