24.45 Electronic flash units for cameras contain a capacitor for storing the energy used to produce the flash. In one such unit, the flash lasts for 1/675 s with an average light power output of 2.70 x 10⁵ W. (a) If the conversion of electrical energy to light is 95% efficient (the rest of the energy goes to thermal energy), how much energy must be stored in the capacitor for one flash? (b) The capacitor has a potential difference between its plates of 125 V when the stored energy equals the value calculated in part (a). What is the capacitance? HINTS: Part (a) is about Physics 1. Energy = Power x Time, so U = 95% of 2.7E+05 x (1/675). Then one can use U = CV2 / 2 for part (b).
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24.45 Electronic flash units for cameras contain a capacitor for storing the energy used to produce the flash. In one such unit, the flash lasts for 1/675 s with an average light power output of 2.70 x 10⁵ W. (a) If the conversion of electrical energy to light is 95% efficient (the rest of the energy goes to thermal energy), how much energy must be stored in the capacitor for one flash? (b) The capacitor has a potential difference between its plates of 125 V when the stored energy equals the value calculated in part (a). What is the capacitance?
HINTS: Part (a) is about Physics 1. Energy = Power x Time, so U = 95% of 2.7E+05 x (1/675). Then one can use U = CV2 / 2 for part (b).
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