Question

A potentiometer wire of length 1m has a resistance of 15 ohm determine the emf of the primary cell which gives a balance

Answer 1

Answer:

1.6V

Explanation:

Given ,

length of wire , l = 100cm

Resistance, R = 10Ω

emf of battery , E1 = 6V

Resistance , R1 = 5Ω

& x = 40 cm

Now , Current , I = E1/R+R1

⇒ I = 6/10+5 = 2/5 A

Also , V = IR

⇒V = 2/5 × 10 = 4V

Now , emf of primary cell = Vx/l

= 4×40/100 = 1.6V

An example of it