A torch bulb is rated 2.5V and 750mA. Calculate its power, its resistance and the energy consumed if this bulb lighted for 4 hours

Question

Physics

Dominique Raymond

31 May, 01:34

A torch bulb is rated 2.5V and 750mA. Calculate its power, its resistance and the energy consumed if this bulb lighted for 4 hours

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Hodges · Answer 1

Using Ohm's Law, we can derived from this the value of resistance. If I=V/R, therefore, R = V/I

Substituting the values to the given,

P = Power = ?

R = Resistance = ?

V = Voltage = 2.5 V

I = Current = 750 mA

R = V/I = 2.5 / (750 x 10^-3)

R = 3.33 ohms

Calculating the power, we have P = IV

P = (750 x 10^-3) (2.5)

P = 1.875 W

The power consumption is the power consumed multiply by the number of hours. In here, we have;

1.875W x 4 hours = 7.5 watt-hours