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

To calculate time, we can use the formula:

$Q = I imes t$

Where:

• $Q$ is the charge (42 C)
• $I$ is the current (200 mA = 0.2 A)
• $t$ is time in seconds.

Rearranging the formula gives us:

$t = \frac{Q}{I} = \frac{42}{0.2} = 210 \, \text{seconds}$

To convert seconds to minutes:

$t = \frac{210}{60} \approx 3.5 \, \text{minutes}$

The energy transferred can be calculated using the formula:

$E = V \times Q$

Where:

• $E$ is the energy transferred (in joules)
• $V$ is the potential difference (6.0 V)
• $Q$ is the charge (42 C)

Thus, substituting in the values:

$E = 6.0 \times 42 = 252 \, \text{J}$

The resistor becomes warm due to collisions between the flowing electrons and the atoms in the lattice structure of the resistor material. As the electrons move through the resistor, they collide with the fixed lattice ions, transferring energy to them. This results in an increase in the vibrational energy of the lattice, which is perceived as a rise in temperature.

Since there are two 100 ohm resistors, if they were arranged in series, the equivalent resistance would be:

$R_{total} = R_1 + R_2 = 100 \, \Omega + 100 \, \Omega = 200 \, \Omega$

Given that the current (I) is 1.2 A and the total voltage (V) is 6.0 V, the required equivalent resistance would be:

$R = \frac{V}{I} = \frac{6.0}{1.2} = 5 \, \Omega$

Since this value (5 ohms) is less than the 200 ohm total resistance, it means the resistors must be connected in parallel, which would allow current to be shared and result in a lower total resistance.