Each of the transformers ( 3 transformers with 240 V)is powered with $100 \mathrm{~W}$, and all have 100 turns on the primary. The number of turns on each secondary varies as $50 \mathrm{~W}$, $200 \mathrm{~W}$ and $100 \mathrm{~W}$, a. Rank the voltage outputs of the secondaries from greatest to least. b. Rank the currents in the secondaries from greatest to least. c. Rank the power outputs in the secondaries from greatest to least.

The three bulbs as we discussed earlier are identical. Rank the bulbs from brightest to dimmest. Explain.

A positive charge is initially at rest in an electric field and is free to move. Does the charge start to move toward a position of higher or lower potential? What happens to a negative charge in the same situation?

$\text {Transformer relationship:} \frac{\text { Primary voltage }}{\text { Number of primary turns }}=\frac{\text { secondary voltage }}{\text { number of secondary turns }}$ The primary of a transformer connected to 120 V has 100 turns. The secondary has 10 turns. Show that the output voltage is 12 V. This is a step-down transformer.

The primary of a transformer connected to $120 \mathrm{~V}$ has 10 turns. The secondary has 100 turns. Show that the output voltage is $1200 \mathrm{~V}$. This is a step-up transformer.

Are wires needed in Maxwell's view of Faraday's law?

Discuss what is wrong with this scheme. To generate electricity without fuel, arrange a motor to run a generator that produces electricity that is stepped up with transformers so that the generator can run the motor and simultaneously furnish electricity for other uses.

An ideal transformer has 50 turns in its primary and 250 turns in its secondary. $12 \mathrm{~V}$ ac is connected to the primary. Find: power supplied to the primary.

A step-up transformer has exactly 50 turns in its primary and exactly 7000 turns in its secondary. If the applied emf in the primary is 120 V, what emf is induced in the secondary?

A transformer has 500 turns in its primary coil and 200 in the secondary coil. a. If an ac voltage of 220 V and frequency 50 Hz is established in the primary coil, find the voltage and frequency induced in the secondary coil. b. If the primary current is 6.0 A, find the current in the secondary coil, assuming an efficiency of 70%.

The primary of an ideal transformer with a turns ratio of 5 is connected to a voltage source with Thevenin parameters

$$v_{Th} = 10 cos 2000t V$$

and

$$R_{Th} = 100 Ω.$$

Determine the average power delivered to a 200-Ω load connected across the secondary winding.

A transformer for a laptop computer converts a $120-\mathrm{V}$ input to a $24-\mathrm{V}$ output. Show that the primary coil has five times as many turns as the secondary coil.

An ideal transformer has 50 turns in its primary and 250 turns in its secondary. $12-\mathrm{V}$ ac is connected to the primary. Show that (a) $60 \mathrm{~V}$ ac is available at the secondary; (b) $6 \mathrm{~A}$ of current is in a $10-\Omega$ device connected to the secondary; and (c) the power supplied to the primary is $360 \mathrm{~W}$.

The primary coil of a transformer has $N_{1}=350$ turns, and the secondary coil has $N_{2}=2000$ turns. If the input voltage across the primary coil is $\Delta v=170 \cos \omega t,$ where $\Delta v$ is in volts and t is in seconds, what rms voltage is developed across the secondary coil?