Danny is competing in the high jump. When he is in the air, his body has _______ energy due to its height, and it has _______ en
1 answer:
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Answer:
Explanation:
For a drop in equilibrium, the weight is equal to the electric force (in magnitude):
where here we have
is the weight of the drop
is the magnitude of the electric force, which can be rewritten as
where
q is the charge of the oil drop
is the magnitude of the electric field
Substituting into the equation and solving for q, we find the charge of the oil drop:
Answer:
Approximately .
Approximately . (assumption: the LED here is an Ohmic resistor.)
Explanation:
The two resistors here and
are connected in parallel. Their effective resistance would be equal to
.
The current in a serial circuit is supposed to be the same everywhere. In this case, the current through the LED should be . That should also be the current through the effective
resistor. Make sure all values are in standard units. The voltage drop across that resistor would be
.
The voltage drop across the entire circuit would equal to
- the voltage drop across the resistors, plus
- the voltage drop across the LED.
In this case, that value would be equal to . That's the voltage that needs to be supplied to the circuit to achieve a current of
through the LED.
Assuming that the LED is an Ohmic resistor. In other words, assume that its resistance is the same for all currents. Calculate its resistance:
.
The resistance of a serial circuit is equal to the resistance of its parts. In this case,
.
Again, the current in a serial circuit is the same in all appliances.
.