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Define (i) potential difference, (ii) capacitance - Leaving Cert Physics - Question 9 - 2009

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Define (i) potential difference, (ii) capacitance. A capacitor stores energy. Describe an experiment to demonstrate that a capacitor stores energy. The ability of ... show full transcript

Worked Solution & Example Answer:Define (i) potential difference, (ii) capacitance - Leaving Cert Physics - Question 9 - 2009

Step 1

(i) the charge stored on each plate of the capacitor;

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Answer

To calculate the charge (q) stored on each plate of the capacitor, use the formula:

q=CVq = CV

Where:

  • C is the capacitance in farads (F)
  • V is the potential difference in volts (V)

Given:

  • C = 64 imes 10^{-6} F (converted from μF)
  • V = 2500 V

Substituting the values:

q=(64imes106)imes2500q = (64 imes 10^{-6}) imes 2500

Calculating that:

q=0.16Cq = 0.16 C

Step 2

(ii) the energy stored in the capacitor;

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Answer

The energy (E) stored in the capacitor can be calculated using the formula:

E=12CV2E = \frac{1}{2} CV^2

Substituting the values:

E=12×(64×106)×(2500)2E = \frac{1}{2} \times (64 \times 10^{-6}) \times (2500)^2

Calculating:

E=200JE = 200 J

Step 3

(iii) the average current that flows through the victim when the capacitor discharges in a time of 10 ms;

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Answer

To find the average current (I), use the formula:

I=qtI = \frac{q}{t}

Where:

  • q = charge (0.16 C from part (i))
  • t = time in seconds (10 ms = 0.01 s)

Substituting the values:

I=0.160.01I = \frac{0.16}{0.01}

Calculating:

I=16AI = 16 A

Step 4

(iv) the average power generated as the capacitor discharges;

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Answer

The average power (P) can be determined using:

P=EtP = \frac{E}{t}

Where:

  • E = energy (200 J from part (ii))
  • t = time (10 ms = 0.01 s)

Substituting the values:

P=2000.01P = \frac{200}{0.01}

Calculating:

P=20000WP = 20000 W

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