Figure 9 shows a lamp connected to a d.c. power supply. The power supply provides a potential difference (voltage) of 4.5 V. The current in the lamp is 0.30 A. (i) Calculate the resistance of the lamp. Use the equation $R = \frac{V}{I}$(1) (ii) Calculate the power supplied to the lamp. power = __________ W Another identical lamp is added to the circuit, as shown in Figure 10. The power supply provides the same potential difference as it provided in the circuit in Figure 9. State and explain the difference between the brightness of the lamp in Figure 9 and the brightness of a lamp in Figure 10. (c) A student is given a low voltage power supply and 1 m of resistance wire. The student uses these and other pieces of equipment to measure the resistance of just 50 cm of the resistance wire. Draw a diagram of the circuit that the student should use. (d) Describe the difference between direct current (d.c.) and alternating current (a.c.) in electrical circuits.

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Figure 9 shows a lamp connected to a d.c - Edexcel - GCSE Physics Combined Science - Question 5 - 2022 - Paper 1

Question 5

Figure 9 shows a lamp connected to a d.c. power supply. The power supply provides a potential difference (voltage) of 4.5 V. The current in the lamp is 0.30 A. (i) ... show full transcript

Worked Solution & Example Answer:Figure 9 shows a lamp connected to a d.c - Edexcel - GCSE Physics Combined Science - Question 5 - 2022 - Paper 1

Step 1

(i) Calculate the resistance of the lamp.

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Answer

To calculate the resistance of the lamp, we can use Ohm's law, which states that resistance is equal to voltage divided by current.

Using the values given: $R = \frac{V}{I} = \frac{4.5 \, \text{V}}{0.30 \, \text{A}} = 15 \, \Omega$

Thus, the resistance of the lamp is 15 Ω.

Step 2

(ii) Calculate the power supplied to the lamp.

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Answer

The power supplied to the lamp can be calculated using the formula:

$P = V \times I$

Substituting the known values: $P = 4.5 \, \text{V} \times 0.30 \, \text{A} = 1.35 \, \text{W}$

Therefore, the power supplied to the lamp is approximately 1.4 W.

Step 3

State and explain the difference between the brightness of the lamp in Figure 9 and the brightness of a lamp in Figure 10.

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Answer

In Figure 9, there is a single lamp connected to the power supply, while in Figure 10, two identical lamps are connected in parallel to the same power supply.

The brightness of a lamp depends on the power it receives. Since both lamps in Figure 10 share the total current from the power supply, each lamp receives less current than the single lamp in Figure 9, making the brightness of each lamp in Figure 10 less than that of the single lamp in Figure 9.

Step 4

Draw a diagram of the circuit that the student should use.

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The circuit diagram should consist of the low voltage power supply connected to the resistance wire with a switch. The circuit can be represented as follows:

Connect the positive terminal of the power supply to one end of the resistance wire.
Connect the other end of the resistance wire to the negative terminal of the power supply.
Include a switch to complete the circuit.

This diagram should clearly label the power supply and the resistance wire.

Step 5

Describe the difference between direct current (d.c.) and alternating current (a.c.) in electrical circuits.

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Answer

Direct current (d.c.) is a type of electrical current that flows in one direction only. This means that the voltage remains constant over time. It is typically generated by batteries or d.c. power supplies.

In contrast, alternating current (a.c.) periodically changes direction. In a.c. systems, the voltage oscillates in polarity, which means the current flow changes direction repeatedly. This is the type of current provided by standard electrical outlets.

Figure 9 shows a lamp connected to a d.c - Edexcel - GCSE Physics Combined Science - Question 5 - 2022 - Paper 1

Worked Solution & Example Answer:Figure 9 shows a lamp connected to a d.c - Edexcel - GCSE Physics Combined Science - Question 5 - 2022 - Paper 1

(i) Calculate the resistance of the lamp.

(ii) Calculate the power supplied to the lamp.

State and explain the difference between the brightness of the lamp in Figure 9 and the brightness of a lamp in Figure 10.

Draw a diagram of the circuit that the student should use.

Describe the difference between direct current (d.c.) and alternating current (a.c.) in electrical circuits.

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