Tma E

TMA E

1. A) Do not use wet hands, and don't stick anything into a plug socket unless it is a plug.

B) If the current flows in only one direction it is called direct current. If the current constantly changes direction, it is called alternating current.

C)i) The earth terminal is connected to the metal casing so that the current goes through the earth wire instead of causing an electric shock. A strong current surges through the earth wire because it has a very low resistance. This breaks the fuse and disconnects the appliance.

ii) It doesn’t need it because the prongs are longer.

D) 2990w

1. A)i) The rod gains negative charge and cloth gains positive because it is easier for a cloth to lose electrons even on supplying very small energy while rubbing

ii) Rub the 2 balloons one by one against the woollen fabric, then try moving the balloons together, do they want to or are they unattracted to each other?

Rub 1 of the balloons back and forth on your hair then slowly it pull it away, ask someone nearby what they can see or if there's nobody else around try looking in a mirror.

Put the aluminium can on its side on a table, after rubbing the balloon on your hair again hold the balloon close to the can and watch as it rolls towards it, slowly move the balloon away from the can and it will follow.

The gold leaf electroscope has a very thin piece of gold foil (called gold leaf) fixed at the top to a piece of copper. The copper has a large round top, called the cap. The whole thing is put inside a glass case, to stop air blowing the delicate gold leaf around. The piece of copper goes through insulation in the top of the glass case, so that any charge on the gold leaf cannot escape. Charge can be transferred to the electroscope by wiping the charged object across the cap. The charge flows over the conducting copper and gold, and the gold leaf rises as it becomes repelled by having the same charge as the copper.

B) The Van de Graaff generator works by static electricity, like shuffling your feet across the carpet and shocking yourself on the doorknob. Big rubber bands move over a piece of felt and strip away the felt's electrons. The electrons move up the rubber band to the metal ball and into the person. The electrons repel each other, so they try to get as far away from each other as possible.

C)i) I guess she could charge all 3 to their "maximum charge" somehow then drop them one by one from the same height through the centre of a wire loop while measuring the voltage across the loop. If the rods are the same length she should see three very similarly shaped pulses with the maximum voltage representing maximum charge.