Electronic flash units for cameras contain a capacitor for storing the energy used to produce the flash. In one such unit, the f
lash lasts for a time interval of 1.45×10−3 s with an average light power output of 2.20×105 W .a) If the conversion of electrical energy to light has an efficiency of 90.0 \% (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?
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?
1 answer:
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Answer:
Choice d. All three balls listed in choice a, b, and c have a momentum of each, same as that of the
ball moving at
. Assumption: all four balls are moving in the same direction.
Explanation:
The momentum of an object is equal to the product of its mass
and its velocity
.
Momentum of a ball moving at
:
.
Similarly:
- Momentum of the ball in choice a:
.
- Momentum of the ball in choice b:
.
- Momentum of the ball in choice c:
.
Hence the conclusion that these balls have the same momentum.
Answer:
Will experience a force due to electric field.
Explanation:
- When a free negative charge is released in an electric field it experiences a force due to the electric field in a direction opposite to the direction of the magnetic field.
According to Coulomb's law this force is mathematically given as:
and, electric field due to a charge is given as:
where:
permittivity of free space
q = magnitude of charge
r = radial distance from the charge