Question

when a 12V battery is connected across an unknown resistor, there is a current of 2.5mA in the circuit. find the value os the resistance

Answer 1

Answer:

V=12v

I=2.5mA=2.5×10^-3 ×10 = 25× 10^-4

R= ?

R=V/I

R=12/25×10^-4

R=12×10^4/25

R=12 × 10000/25

R =4800

Therefore, R = 4800 ohms

Answer 2

Given that, a 12V battery is connected across an unknown resistor, there is a current of 2.5mA in the circuit.

We have to find the value of resistance.

From above data we have, Potential difference i.e. V = 12V and Current i.e. I = 2.5 mA.

Firstly, convert mA into A. To do this, divide the given value by 1000.

I = 2.5 mA = 2.5 × 10^-3 A

Now,

Ohm's law: The potential difference i.e. V across the ends of the wire is directly proportional to the square of current i.e. I flowing through that wire provides the temperature remains constant.

V ∝ I

V = IR (here, R is constant)

From ohm's law we can say that,

V = IR (where R is resistance)

12 = 2.5 × 10^-3 × R

12/(2.5 × 10^-3) = R

(12 × 10^3)/2.5 = R

12000/2.5 = R

4.8 × 10^3 = R

Therefore, the value of resistance is 4.8 × 10^3 ohm.