Question

A platinum wire has resistance of 2.5 ohm if its temperature coefficient of resistance is 4×10-³/°c find the change in resistance when temperature changes to 70°c​

Answer 1

Given :

Resistance of the wire = 2.5Ω

Change in temperature = 70°C

Coefficient of resistance = 4×10‾³ °C‾¹

To Find :

Change in resistance.

Solution :

❖ Resistance of a conductor depends on the various factors like length, area of cross section and temperature.

• Change in resistance of a conductor is directly proportional to the change in temperature. (∆R ∝ ∆T)
• Change in resistance of a conductor is also directly proportional to the initial resistance. (∆R = R｡)

From the both equations:

$\dag\:\underline{\boxed{\bf{\orange{\Delta R=R_o\alpha\Delta T}}}}$

Where α denotes coefficient of resistance

By substituting the given values;

➙ ∆R = R｡α ∆T

➙ ∆R = 2.5 × (4 × 10‾³) × 70

➙ ∆R = 700 × 10‾³

➙ ∆R = 0.7 Ω