Grade 10 Science — Magnetic effects of electric current
Read a field-line diagram for direction and strength, pick the right-hand thumb rule or Fleming's left-hand rule for the job, and explain what the earth wire and the fuse are doing in a house circuit.
Name: ________________________
1.Why are the appliances in a house wired in parallel with one another?
- a) So that the total resistance rises with each appliance added
- b) So that each carries the same current
- c) So that switching one off switches them off
- d) So that each has the same potential difference across it
2.Field lines round a bar magnet are drawn below. Tap the part of the picture where the field is strongest.
Write the number of the part.
3.What is short-circuiting?
- a) The live wire and the neutral wire coming into direct contact
- b) Too many appliances plugged into one socket
- c) The earth wire breaking away from its plate
- d) A drop in the supply voltage
4.A single circular turn of wire makes a field of a certain strength at the center of the loop. A coil of 12 such turns carries the same current. How many times that strength is the field at the center now? Answer with a number.
5.Sort each job by the rule that does it.
Groups: Right-hand thumb rule · Fleming's left-hand rule
- Turning a corkscrew along the current to find the field
- Finding which way a current-carrying rod is pushed in a field
- Finding which way a moving electron is pushed in a field
- Finding which way the field lines wrap round a straight wire
6.Outside a bar magnet, which way do the field lines run?
- a) From the middle of the magnet outwards at both ends
- b) Into both poles from the surrounding space
- c) Out of the north pole and into the south pole
- d) Out of the south pole and into the north pole
7.A coil of many circular turns of insulated copper wire, wound closely in the shape of a cylinder, has a name of its own. What is it? Answer with one word.
8.A piece of soft iron is put inside a solenoid and the current is switched on. What has been made?
- a) A fuse
- b) An electric generator
- c) A rheostat
- d) An electromagnet
Answer key — Grade 10 Science — Magnetic effects of electric current
- 1. d) So that each has the same potential difference across it
- 2. 1 — Close to the end of the magnet, where the lines are crowded
- 3. a) The live wire and the neutral wire coming into direct contact
- 4. 12
- 5. Finding which way the field lines wrap round a straight wire → Right-hand thumb rule; Turning a corkscrew along the current to find the field → Right-hand thumb rule; Finding which way a current-carrying rod is pushed in a field → Fleming's left-hand rule; Finding which way a moving electron is pushed in a field → Fleming's left-hand rule
- 6. c) Out of the north pole and into the south pole
- 7. solenoid
- 8. d) An electromagnet