# Problems: Electromagnetic effects

Fill in the missing words:

1. The lines of . . . . . . . . . . . . . . . . . . round a straight current-carrying conductor are in the shape of . . . . . . . . . . . . . . . . . . .
2. The Right-hand Grip Rule:
if you grip the . . . . . . . . . . . . . . . . . . with your right. . . . . . . . . . . . . . . . . . pointing with the . . . . . . . . . . . . . . . . . ., your fingers curl with the  . . . . . . . . . . . . . . . . .  field lines.
3. For a solenoid, the magnetic field is like that of a . . . . . . . . . . . . . . . . . .
4. If a coil is viewed from one end and the current flows in an anti-clockwise direction, then this end is a . . . . . . . . . . . . . . . . . . -pole.
5. The magnetic effect of a coil can be increased by  increasing the number of . . . . . . . . . . . . . . . . . . .
increasing the . . . . . . . . . . . . . . . . . . or inserting a . . . . . . . . . . . . . . . . . . core.

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1. When there is a relative movement between a wire and a magnetic . . . . . . . . . . . . . . . . . . then . . . . . . . . . . . . . . . . . . may be . . . . . . . . . . . . . . . . . . in the wire.
2. Fleming’s Rule for the dynamo effect uses the . . . . . . . . . . . . . . . . . . hand.
3. Lenz’s Law: the . . . . . . . . . . . . . . . . . . of the . . . . . . . . . . . . . . . . .  current is such that it . . . . . . . . . . . . . . . . .  the change producing it.
4. The strength of the induced current depends on the . . . . . . . . . . . . . . . . . of the movement, the . . . . . . . . . . . . . . . . . of the magnet and the number of . . . . . . . . . . . . . . . . .  on the coil.
5. An a.c. generator is fitted with . . . . . . . . . . . . . . . . . whereas a.c. generator is fitted with a . . . . . . . . . . . . . . . . .
6. A transformer will work only with . . . . . . . . . . . . . . . . . . . . . .  current.
7.  The formula for a transformer is:

When the voltage is stepped-down, the current is stepped-. . . . . . . in the   . . . . . . . . . . . . ratio (if the transformer is . . . . . . . % efficient).

8. The core of a transformer is . . . . . . . . . . . . . . . . . . . . . to reduce  . . . . . . . . . . . . . .
9.  In the national Grid system, the electricity is distributed round the country at  . . . . . . . . . . . .  voltage and . . . . . . . . . . . . . . . . . current.
10. In the Grid,  . . . . . . . . . . . . . . . . . . . current is used because transformers will not work with . . . . . . . . . . . . . . . current.