Grade 11 · Science · Physics

11th grade A changing magnetic field makes a current: generators and transformers worksheet

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A changing magnetic field makes a current: generators and transformers

Grade 11 Science Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

A transformer's primary coil has 500 turns and gets 120 V. Its secondary coil has 50 turns. What voltage comes out, Ari?
A transformer's primary coil has 100 turns and gets 240 V. Its secondary coil has 25 turns. What voltage comes out, Bo?
A transformer's primary coil has 50 turns and gets 12 V. Its secondary coil has 200 turns. What voltage comes out, Esme?
4.
In the diagram, the magnet is held still inside the coil. What does the needle show, Jun?
- A steady swing right
- Zero
- A swing left
5.
In the diagram, the magnet is pulled back out. Which way does the needle swing, Kira?
Use the picture in question 4.
- Left
- It doesn't move
- Right, as before
6.
What makes a current flow in a coil with no battery, Milo?
- Warming the coil
- A changing magnetic field through it
- A magnet resting beside it
7.
A coil is moved past a magnet that stays still. Is a current made, Noah?
- No: coils can't make current
- Yes: the field through the coil changes
- No: the magnet must move
8.
A coil with more turns is used with the same moving magnet. What happens to the current, Pia?
- It stays the same
- It gets smaller
- It gets bigger
9.
A transformer has 100 turns on its primary coil and 1000 on its secondary. What kind is it, Ren?
- Step-down
- Step-up
- Neither
10.
A phone charger's transformer has fewer turns on its secondary coil. What does it do to the voltage, Tala?
- Raises it
- Leaves it the same
- Lowers it

A changing magnetic field makes a current: generators and transformers. Every version has 10 questions, and the answer key prints on the second page.

I can say what makes an induced current: the magnetic field through a coil must change. A faster change or more turns gives a bigger current; reversing the change reverses it.
I can find a transformer's secondary voltage from Vs ÷ Vp = Ns ÷ Np and say whether it steps up or down.
I can use VpIp = VsIs for an ideal transformer: stepping voltage up steps current down, and power out is never more than power in.
I can explain why power lines run at high voltage (smaller current, much smaller I²R heating) and how generators, bike dynamos and wireless chargers use induction.

Standard: HS-PS2-5

induced current: A current made by a changing magnetic field, with no battery

primary coil: The transformer coil the current goes into

secondary coil: The transformer coil the changed current comes out of

step-up / step-down: A transformer that raises / lowers the voltage

alternating current (AC): Current that keeps reversing direction

Your child flipped the ratio. For a transformer, Vs ÷ Vp = Ns ÷ Np, and in an ideal one the current changes the opposite way.

Your child did not square the current. Heating loss in a line is P = I²R.

Your child thought a transformer makes extra energy. It changes voltage and current, but power out can't be more than power in.

What is the most common mistake with a changing magnetic field makes a current: generators and transformers?

Your child flipped the ratio. For a transformer, Vs ÷ Vp = Ns ÷ Np, and in an ideal one the current changes the opposite way.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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