Question

A bulb is rated at 4W ,10V
(a) find the resistance of the bulb and safe current for its maximum glow
(b) how can you run it at 20V safely
(c) find the power consumed when two such bulbs are connected to a 5V supply in (i) series (ii) parallel

Answer 1

Answer:

P= 4W

V=10V

we know that P=VI

P=V²/R. ( Ohm's law)

4=100/R

R=100/4

R=25Ω

we also know

V=IR

I=V/R

I=10/25

I=0.4 A

If V=20V

P=VI

I=P/V

I=4/20

I=1/5

I= 0.2 A

P=V²/R

So for total resistance for (i) series

R=R1+R2

R=25+25

R=50Ω

P=5²/50

P=25/50

P=1/2

P=0.5W

And now for (ii) parallel

1/R=1/R1+1/R2

1/R=1/25

R=25

P=V²/R

P=25/25

P=1W

I HOPE THIS WILL HELP YOU AND PLEASE MARKET AS BRAINLIEST ANSWER!!!