The magnetic field around a straight current-carrying wire forms circular loops, and a current-carrying solenoid behaves like a bar magnet, so this Year 11 sheet starts with the two basic field shapes. More turns on the coil is the listed way to strengthen it.
Key Takeaways
The field around a straight current-carrying wire is circular (Q1).
A current-carrying solenoid behaves like a bar magnet (Q2).
Q5 records adding more turns to strengthen the field.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.The magnetic field around a straight current-carrying wire is which shape?
(a) circular(b) straight lines(c) spiral(d) parallel to the wire
2.A solenoid carrying a current behaves like which of the following?
(a) a bar magnet(b) a capacitor(c) a resistor(d) a diode
3.Which of these is an advantage of an electromagnet over a permanent magnet?
(a) its strength can be changed and it can be switched off(b) it never loses its magnetism(c) it is always stronger(d) it needs no electric current
4.Fleming's left-hand rule gives the direction of the force on what?
(a) a current-carrying wire in a magnetic field(b) a falling object(c) a stationary electric charge(d) a beam of light
5.The strength of an electromagnet can be increased by doing what?
(a) adding more turns to the coil(b) using a plastic core(c) reducing the current(d) removing the iron core
6.A step-up transformer does which of the following?
(a) increases the voltage(b) decreases the voltage(c) changes d.c. into a.c.(d) increases the power
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Describe the shape of the magnetic field around a straight current-carrying wire.
8.What is a solenoid?
9.Give two ways to increase the strength of an electromagnet.
10.What is the difference between an electromagnet and a permanent magnet?
11.State the motor effect.
12.State one use of a relay.
13.How does a loudspeaker use the motor effect?
14.Why will a transformer not work when supplied with direct current (d.c.)?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A wire of length 0.4 m carries a current of 3 A in a magnetic field of flux density 0.5 T. Using F = B × I × L, calculate the force on the wire.
16.A transformer has 300 primary turns and 60 secondary turns with a 120 V primary supply. Using Vp ÷ Vs = Np ÷ Ns, calculate the secondary voltage.
17.A transformer has 200 primary turns and 1000 secondary turns with a 50 V primary supply. Using Vp ÷ Vs = Np ÷ Ns, calculate the secondary voltage.
18.An ideal transformer steps 240 V down to 12 V. The secondary current is 4 A. Using P = V × I, calculate the power and then find the primary current.
19.A transformer has 200 primary turns and a 240 V primary supply. It produces a 12 V output. Using Np ÷ Ns = Vp ÷ Vs, calculate the number of secondary turns.
20.A transformer is 90% efficient. Its input power is 100 W. Calculate the useful output power.
Answer Key
1. a) circular
2. a) a bar magnet
3. a) its strength can be changed and it can be switched off
4. a) a current-carrying wire in a magnetic field
5. a) adding more turns to the coil
6. a) increases the voltage
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What shape is the magnetic field around a straight current-carrying wire?
Circular, option (a) in this worksheet (Q1).
What does a current-carrying solenoid behave like?
A bar magnet, option (a) in this worksheet (Q2).
How can the field be strengthened?
Add more turns to the coil, option (a) in this worksheet (Q5).
Stuck on a similar problem? Clear your next doubt instantly with the Doubt Solver.
Browse more free worksheets for IGCSE Year 11.