NIOS Physics Viva Questions with Solutions

Question 1: What are ohmic and non-ohmic resistances?

Answer: Resistances which obey Ohm’s law are called ohmic resistances, e.g., metals like Cu, Al, Ag, etc. at low temperature.

Resistances which do not obey Ohm’s law are called non-ohmic resistances, e.g., diodes and transistors.

Question 2: Give common examples of non-ohmic resistances.

Answer: Vacuum tube diodes, semi-conductor diodes and transistors are non-ohmic resistances.

Question 3: Name some substances whose resistance decreases with increase in temperature.

Answer: Resistance of semi-conductors (Si, Ge) decreases with increase in temperature.

Question 4: What are the factors affecting the resistance?

Answer: The resistance depends upon length, area of cross-section, nature of material and temperature of the conductors.

Question 5: What is the condition for a Wheatstone bridge to become balanced?

Answer: In a balanced Wheatstone’s bridge, we have

 P/S = R/S

Question 6: Will the interchange of positions of cell and galvanometer affect the balance condition?

Answer: No. The condition of balanced Wheatstone bridge remains satisfied.

Question 7: What is galvanometer?

Answer: A galvanometer is a sensitive electromagnetic instrument used to detect and measure small electric currents in a circuit.

Question 8: On what factors does the angle of deviation depend?

Ans. The angle of deviation depends upon the following factors:

(i) The angle of incidence

(ii) The refracting angle of the prism

(iii) The material of the prism (Refractive Index)

(iv) The colour of the light used, i.e., wavelength of light

Question 9: What is the speciality about minimum deviation?

Ans. Under minimum deviation condition, light ray travels inside the prism parallel to the base of the prism and the angle of incidence = angle of emergence.

Question 10: Does the angle of minimum deviation depend upon the colour of light used?
Ans. Yes, it is different for different colours or wavelengths.

Question 11: Which colour will travel (i) fastest (ii) slowest in prism?
Ans.

(i) Fastest – Red
(ii) Slowest – Violet

Question 12: Which Color deviates most and which one is least?

Ans. Voilet is deviates most and red deviates least.

Question 13: Name different types of energy bands.
Ans. Different energy bands are:

1. Conduction band (C)
2. Valence band (V)
3. Forbidden band (F)

Question 14: Define a hole.
Ans. A place vacated by an electron is called a hole. It is associated with a positive charge.

Question 15: Define an intrinsic semiconductor.

Ans. A pure semiconductor material is called an intrinsic semiconductor.

Question 16: Which materials are commonly used as semiconductors?

Ans. Silicon and germanium are commonly used as semiconductors.

Question 17: Define an extrinsic semiconductor.
Ans. A semiconductor material made deliberately impure is called an extrinsic semiconductor.

Question 18: What is doping?

Ans. The process of adding a suitable impurity to pure semiconductor, deliberately, is called doping.

Question 19: What is biasing of a junction?

Ans. Applying an external potential difference more than potential barrier on the faces of the junction is called biasing of the junction.

Question 20: How does the bias affect the thickness of the depletion layer?
Ans.

• Forward bias decreases the thickness of depletion layer.
• Reverse bias increases the thickness of depletion layer.