Physics 2008 JAMB Past Questions - Question 40: An electric generator has an emf of 240V and an internal resistance of 1Ὡ.if the current supplied by the generator is 20A when the terminal voltage is 220V ,find the ratio of the power supplied to the power dissipated.

Correct Answer

C

Explanation

Power supplied = IE = 20x 240 = 4800wpower dissipated = IV = 20 x 220 = 4400WTo find the ratio of the power supplied to the power dissipated in the electric generator, you can use the formula for electrical power:

Power (P) = Voltage (V) × Current (I)

First, let's find the power supplied by the generator and the power dissipated in its internal resistance.

1. Power Supplied (P_supplied):
The power supplied by the generator is the product of the EMF (Electromotive Force) and the current it generates. Since the EMF is 240V and the current is 20A:

P_supplied = EMF × Current
P_supplied = 240V × 20A
P_supplied = 4800 watts (W)

2. Power Dissipated in Internal Resistance (P_dissipated):
The power dissipated in the internal resistance is the product of the current passing through the internal resistance and the square of the internal resistance (due to Ohm's law). The internal resistance is 1Ω, and the current is 20A:

P_dissipated = Current² × Internal Resistance
P_dissipated = (20A)² × 1Ω
P_dissipated = 400W

Now, to find the ratio of power supplied to power dissipated:

Ratio = P_supplied / P_dissipated
Ratio = 4800W / 400W
Ratio = 12

So, the ratio of the power supplied to the power dissipated is 12:1.

= power supplied = 4800 w = 12/11power dissipated = 4400wTo find the ratio of the power supplied to the power dissipated in the electric generator, you can use the formula for electrical power:

Power (P) = Voltage (V) × Current (I)

First, let's find the power supplied by the generator and the power dissipated in its internal resistance.

1. Power Supplied (P_supplied):
The power supplied by the generator is the product of the EMF (Electromotive Force) and the current it generates. Since the EMF is 240V and the current is 20A:

P_supplied = EMF × Current
P_supplied = 240V × 20A
P_supplied = 4800 watts (W)

2. Power Dissipated in Internal Resistance (P_dissipated):
The power dissipated in the internal resistance is the product of the current passing through the internal resistance and the square of the internal resistance (due to Ohm's law). The internal resistance is 1Ω, and the current is 20A:

P_dissipated = Current² × Internal Resistance
P_dissipated = (20A)² × 1Ω
P_dissipated = 400W

Now, to find the ratio of power supplied to power dissipated:

Ratio = P_supplied / P_dissipated
Ratio = 4800W / 400W
Ratio = 12

So, the ratio of the power supplied to the power dissipated is 12:11.