## 1. What is the unit of resistance ?

1. Henry
3. Ohm
4. Tesla

Memory: Ohm is the practical and SI unit of resistance.

## 2. The electrical resistance of insulators is ?

1. High
2. Very high
3. Low
4. Very low

Memory: Resistance of insulators is very high due to the fact that, it has very few free electrons and strongly opposes the follow of electron.

## 3. What is the cause of resistance ?

1. Movement of free electrons
2. Movement of ions
3. collision of ions and free electrons
4. Friction

Memory: When free electrons moving through a conductor, collision occur between free electrons and ions of the metal (of which it is made of). Results in, a hindrance or resistance creates in the path of flow of electrons.

## 4. SI unit of resistance is ?

2. Henry
3. Ohm
4. Ohm-meter

Memory: SI unit of resistance is “Ohm”.

## 5. On what factors does the resistance of a conductor depend on ?

1. Length of the conductor
2. Cross-sectional area of the conductor
3. Material of the conductor
4. All of the above

Memory: Resistance of a conductor is defined mathematically as, R=ρ*L/A. Where,

• R = Resistance
• ρ = The nature of the material.
• L = Length of the conductor.
• A =Area of the conductor.

## 6. Electrical resistivity of a given metallic wire depends upon ?

1. Nature of the material
2. Length of the material
3. Width of the material
4. None of the above

Memory: Resistivity is also known as specific resistance of the material having unit length and unit cross-sectional area.

The resistance between opposite faces of a unit cube of that material.

## 7. Three resistances each of R ohm connected in such a way to form a triangle. The resistance between any two points of the triangle will be ?

1. R Ω
2. 3/2 Ω
3. 3 Ω
4. 2/3 Ω

Memory: It’s answers can be found using series-parallel combination of resistances.

## 8. Find the equivalent resistance between points a and b of the above circuit ?

1. 5 Ω
2. 10 Ω
3. 3.33 Ω
4. 2 Ω

Memory: The answer can be found by using “series-parallel combination” of resistances.

## 9. An electric bulb is rated 220V and 100W . What is the resistance of the filament ?

1. 200 Ω
2. 484 Ω
3. 584.5 Ω
4. 220 Ω

Memory: The answer can be found by using the following formula – (R = V^2/W).

## 10. Reciprocal of specific resistance is ?

1. Specific reluctance
2. Specific capacitance
3. Specific conductance
4. Specific inductance

Memory: Specific resistance is also known as Resistivity and it’s the reciprocal of conductivity.

It is measured in ohm-m.

## 11. The temperature co-efficient of resistance of conductors is ?

1. Negative
2. Positive
3. Neutral
4. Varied with change in temperature