Question

A torch bulb is rated 5 volt and 500 milliampere calculate (a) its power (b)its resistance and (c) the energy consumed if this bulb is lighted for 4 hours

Answer 1

Explanation:

Power=voltage×current

P=V×I

P=2.5 watt.

$5 \times 500 { \times 10}^{ - 3}$

by ohm's law V=IR

• 5= 0.5×R
• R=10 Ohm.

also H=VIt

• H=5×0.5×3600
• H=9000 Joule

Answer 2

Explanation:

Here Potential difference, V= 5v Current, I=500mA=500/1000A =0.5A Now, a) Power = V.I =5*0.5 =2.5W b) From ohm's law, V=RI R=V/I =5/0.5 =10 ohm c) Time for which the bulb is lighted, t =4 h =4*3600s =14400s Energy consumed, H =VIt = 5*0.5*14400 =36000J