1) When wiring a house, it is important to use the correct cables. The current ratings of four different cables are listed. All four cables are used in series in the same circuit. Which cable is most likely to overheat? A 6A B 10A C 15A D 30A 2) What is an electric current in a metal wire? A a flow of electrons B a flow of neutrons C a flow of nucleons D a flow of protons 3) Four wires are made of the same metal. Which wire has the greatest resistance? A a 100 cm long wire with a diameter of 3.0 mm B a 100 cm long wire with a diameter of 6.0 mm C a 10 cm long wire with a diameter of 3.0mm D a 10 cm long wire with a diameter of 6.0mmA student uses four ammeters P. Q. R and S to measure the current in different parts of the circuit shown. Which two ammeters read the largest current? A P and Q B Pand R C R and Q D R and S 5) A circuit X is set up with two identical lamps. Circuit Y is then set up, changing the positions of the meters. X On which meters do the readings change? A both the ammeter and the voltmeter B the ammeter only C the voltmeter only D neither the ammeter nor the voltmeterAn electrical appliance is powered from a mains supply. The appliance normally uses a current of 3 A, but the current briefly rises to 4 A at the instant the appliance is switched on. The cable to the appliance is designed for currents up to 6A. A fuse is used to protect the circuit. What should be the rating of the fuse? A 1A B 3A C 5A D 13A 7) A transformer is needed to convert a supply of 240 Va.c. into 4800 Va.c.. Np Ns 240 Va.c. 4800 Va.c. Which pair of coils would be suitable for this transformer? number of turns number of turns on primary coil Np on secondary coil Ns 50 1000 240 48 000 480 24 2000 100 8) There is a current in a variable resistor when a potential difference (p.d.) is applied across it. In which situation is the current increased? A Decrease the p.d. and keep the resistance the same. B Decrease the p.d. and increase the resistance. C Keep the p.d. the same and decrease the resistance. D Keep the p.d. the same and increase the resistance.10) The diagram shows a wire carrying a current in the direction shown. There is a magnetic field acting from left to right. The wire experiences a force acting out of the page. direction wire of current direction of magnetic field The current is now reversed. In which direction does the force on the wire now act? A into the page B out of the page C to the left D to the right11) A student sets up four experiments using bar magnets and other metal objects. The N and S poles of the bar magnets are labelled N and S. 2 S S S N iron 3 4 S copper S N N S Which pairs attract each other? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4 12) The diagrams show a current-carrying wire with an arrow in the direction of the current. Which diagram shows the magnetic field produced by the current? A B H magnetic magnetic field lines field lines wire wire C D magnetic magnetic field lines field lines wire wire