Question

A torch bulb is rated 5 V and 500 mA. Calculate Its

1. Power
2. Resistances
3. Energy consumed when it is lighted for 2½ hours.

Answer 1

(i) P = V × I

= 5 V × 0.5 A

= 2.4 W

(ii) Resistances (R) = `"V"/"I"`

= `5/0.5`

= 10 ohms

(iii) Energy consumed = P × t

= 2.4 W × 2.5 h

= 6.25 Wh