Question 67: Current Electricity

Question

The current drawn by the primary coil of an ideal transformer, which steps up $$22 \mathrm{~V}$$ into $$220 \mathrm{~V}$$, to operate a device having a load resistance $$110 \Omega$$ is:

Accepted Answer

To find the current drawn by the primary coil of the transformer, we can use the concept of power conservation in an ideal transformer. The power input to the primary coil is equal to the power output from the secondary coil. The formula for power is $$P = IV$$, where $$I$$ is current and $$V$$ is voltage.
Given that the transformer steps up the voltage from $$22 \mathrm{~V}$$ to $$220 \mathrm{~V}$$ and the load resistance on the secondary side is $$110 \Omega$$, we can first calculate the current in the secondary circuit using Ohm's law, $$V = IR$$, where $$V$$ is voltage, $$I$$ is current, and $$R$$ is resistance. Rearranging this, we get $$I = \frac{V}{R}$$.
The voltage across the secondary coil (and hence across the load resistance) is $$220 \mathrm{~V}$$, and the load resistance is $$110 \Omega$$. Thus, the current in the secondary circuit is:
$$I_{	ext{secondary}} = \frac{220 \mathrm{~V}}{110 \Omega} = 2 \mathrm{~A}$$
Now, according to the principle of an ideal transformer (neglecting any losses), the power in the primary coil is equal to the power in the secondary coil. Thus,
$$P_{	ext{primary}} = P_{	ext{secondary}}$$
Applying the formula for power ($$P = IV$$) in both coils, we have:
$$I_{	ext{primary}} 	imes V_{	ext{primary}} = I_{	ext{secondary}} 	imes V_{	ext{secondary}}$$
We know $$V_{	ext{primary}} = 22 \mathrm{~V}$$, $$V_{	ext{secondary}} = 220 \mathrm{~V}$$, and we've calculated $$I_{	ext{secondary}} = 2 \mathrm{~A}$$. Plugging these values into the equation, we get:
$$I_{	ext{primary}} 	imes 22 = 2 	imes 220$$
Solving for $$I_{	ext{primary}}$$:
$$I_{	ext{primary}} = \frac{2 	imes 220}{22} = \frac{440}{22} = 20 \mathrm{~A}$$
Therefore, the current drawn by the primary coil of the transformer is
20 A
.
The correct answer is
Option A
20 A
.

Answer

20 A

Answer

1 A

Answer

2 A

Answer

10 A

Current Electricity

The current drawn by the primary coil of an ideal transformer, which steps up $22 \mathrm{~V} into 220 \mathrm{~V}, to operate a device having a load resistance 110 \Omega$ is:

Choose the correct answer: