9.1 A simplified diagram of a DC electric motor is shown below - NSC Physical Sciences - Question 9 - 2023 - Paper 1

The motor converts electrical energy into mechanical energy, enabling rotational motion.

The coil will rotate CLOCKWISE if the current flows in the specified direction.

1. Increase the strength of the magnetic field by using stronger magnets or bringing magnets closer together.
2. Increase the current by using a higher voltage power supply.

Root mean square current (I_rms) is defined as the effective value of an alternating current (AC) that dissipates the same amount of energy in a resistor as an equivalent direct current (DC).

To calculate the root mean square current, use the formula:

$I_{rms} = \frac{I_{max}}{\sqrt{2}}$

Substituting the given maximum current:

$I_{rms} = \frac{3.6}{\sqrt{2}} \approx 2.55 \text{ A}$

To calculate the energy consumed, use the formula:

$W = P \times t$

Where Power (P) can be found using:

$P = I_{rms}^2 \times R$

Assuming the voltage is 220 V and using:

$R = \frac{220}{2.62} \approx 83.97 \text{ ohms}$

Calculating Power:

$P = (2.62)^2 \times 83.97 \approx 576.4 ext{ W}$

Now, calculate energy for two minutes (120 seconds):

$W = 576.4 \times 120 \approx 69,168.48 ext{ J}$