The value of X for which the galvanometer in the figure shows a null deflection is:
4Ω.
8Ω.
1Ω.
4.5 Ω.
The set up in the figure is used to study the relationship between current (I) and potential difference (V) for a wire X.
The ammeter is connected as shown because it has:
Very high resistance and so allows high current to flow through it.
Very low resistance and so alters the current flowing through it.
Very low resistance and so does not alter the current flowing through it.
A very high resistance and so allows little current to flow through it.
The heating element of an electric kettle has a resistance of 30.0 Ω.
The kettle is connected to an a.c. power supply of root means square voltage 230 V.
The peak value of the current is:
7.7 A.
15.2 A.
10.8 A.
5.4 A.
If the material X is a copper wire, the relationship between V and I when the switch is closed at constant temperature is:
Ohm’s law.
Lenz’s law.
Hooke’s law.
Coulomb’s law.
Which of the following statements describes an electric generator?
An electrical current causes a coil of wire to rotate in a magnetic field.
Electric potential in a rotating coil of a wire creates a temporary magnet.
A coil of wire is rotated through a strong magnetic field to produce an electric current.
Forces from a permanent magnet allow a coil of wire to rotate.
