A resistor is connected to a power supply - Edexcel - GCSE Physics Combined Science - Question 5 - 2018 - Paper 1

To calculate the time taken for a charge (Q) of 42C to flow through a resistor with a current (I) of 200 mA (which is 0.2 A), we can use the formula:

$Q = I imes t$

Rearranging gives: $t = \frac{Q}{I} = \frac{42C}{0.2A} = 210 minutes$.

Therefore, the time taken is 210 minutes.

The total energy (E) transferred by the power supply can be calculated using the formula:

$E = V imes Q$

where V is the voltage and Q is the charge. Thus,

$E = 6.0V \times 42C = 252 J$.

So, the energy transferred is 252 joules.

The resistor becomes warm due to collisions between the moving electrons and fixed atoms in the resistor's lattice structure. As current flows, electrons collide with these ions, causing them to vibrate more vigorously. This increase in vibration leads to a rise in temperature, resulting in the resistor warming up.

Given that two 100 ohm resistors are connected between P and Q with a total current of 1.2 A and a potential difference of 6.0 V:

1. If the resistors were in series, the total resistance would be: $R = R_1 + R_2 = 100\Omega + 100\Omega = 200\Omega$.
2. The current through such a configuration would be: $I = \frac{V}{R} = \frac{6V}{200\Omega} = 0.03 A$, which is less than 1.2 A.

Thus, since the total current exceeds 0.3 A, the resistors must be connected in parallel.