12.4

Question 1

What is Ohm’s Law?

Answer 1

It is the relationship between the potential difference in a conductor and the current flowing through it.

Question 2

Nichrome

Answer 2

Nichrome is an alloy of nickel, chromium, manganese and iron.

Question 3

State Ohm’s Law.

Answer 3

The potential difference, V, across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains the same. This is called Ohm’s law.

Question 4

Derive V=IR

Answer 4

V ∝ I
or V/I = constant = R
or V = IR

Question 5

What is Resistance?

Answer 5

R is a constant for the given metallic wire
at a given temperature and is called its resistance. It is the property of a conductor to resist the flow of charges through it.

Question 6

Resistance is the property of a conductor to resist the flow of charges through it. What is its SI unit?

Answer 6

Its SI unit is ohm, represented by the Greek letter Ω.

Question 7

Define an Ω.

Answer 7

One Ohm is the resistance in a conductor when the potential difference between its ends is 1V and the current flowing through it is 1A.

1 ohm = 1 volt /1 ampere
1Ω = 1V/1A

Question 8

What is the relationship between resistance and current?

Answer 8

The current through a resistor is inversely proportional to its resistance. If the resistance is doubled the current gets halved.

Question 9

Variable resistance or rheostat.

Answer 9

In many practical cases it is necessary to increase or decrease the current in an electric circuit. A component used to
regulate current without changing the voltage source is called variable resistance. In an electric circuit, a device called rheostat is often used to change the resistance in the circuit.

Question 10

What happens to electrons when resistance is applied?

Answer 10

Thus, motion of electrons through a conductor is retarded by its resistance.