Question

40 lamps, each of resistance 4 ohms are connected in series to 240V supply in order to
decorate a tree
calculate
a)the current in each lamp
b)the power dissipated in each lamp
show your working and write units

Answer 1

Given:-

• Resistance of Lamp ,R = 4 ohm

• No. of lamps = 40

• Potential Difference ,V = 240 V

To Find:-

• (a)the current in each lamp ,I

• (b)the power dissipated in each lamp ,P

Solution:-

Using Ohm's Law

• V = IR

where,

V is the Potential Difference

I is the Current

R is the Resistance

Substitute the value we get

→ 240 = I×4

→ I = 240/4

→ I = 60 A

Therefore,the current through the each lamp is 60 Ampere.

Now, Calculating the Power dissipate in each lamp

• P = VI

where,

P is the power

V is the Potential Difference

I is the Current

Substitute the value we get

→ P = 240×60

→ P = 14400 W

Therefore,the power dissipate through each lamp is 14400 Watts.

Total power dissipate by 40 Lamps = 40 × 14400 = 576000 Watts.