Efficiency is calculated through dividing the actual mechanical advantage by the hypothetical mechanical advantage:
- the actual mechanical advantage is 9J because that's how much work the light bulb doing
- the hypo. mechanical advantage is 100J. Ideally, in a perfect world, the light bulb can convert 100J input into 100J output, but do to resistance and other factors it is not possible.

change the decimal to a percentage:

the light bulb had 9% efficiency
Answer:
The current in the circuit increases
Explanation:
The ohm's law states that the potential across a circuit is proportional to the current in the circuit.
V ∝ I
Where 'V' is the potential difference across the circuit and 'I' is the current in the circuit.
The proportionality constant present in the equation is the resistance of the circuit. Hence, the equation becomes
V = IR
According to the equation, when V is directly proportional to 'I' where 'R' remains as constant, then the change in 'V is brings change in 'I' to make the equation valid.
So, when there is an increase in the voltage, the current on the circuit increases.
Answer:
B, B (decreases, a clockwise)
Explanation:
Finally, the switch on the electromagnet is reopened. The magnitude of the external magnetic flux through the wire loop <u>decreases</u>, and there is <u>a clockwise</u>, current induced in the loop (as seen from the left).