An analog ammeter and voltmeter of suitable ranges are to be used to measure the current and voltage?

Question

of an electric lamp. If a mistake was made and the meters were interchanged, what will happen?

Answer 1

the voltmeter is usually used in parallel (with your lamp) and has a high resistance to attract (or take away) as little of the current away from the lamp. if used in series it would lower the voltage that can be dropped across the lamp and lower the over all current flow. the ammeter is meant to be used in series and has low resistance to have minimal impact on the voltage drop across it. if used in parallel across the lamp it would attract all the current, taking it away from the lamp (bypassing the lamp)

Answer 2

Connecting the ammeter alone across the supply will cause a high current to flow which will either pop a fuse or breaker or cause the shunt resistor inside the meter to go up in smoke.

Connecting a voltmeter in series will do no harm, the meter will just read the value of the supply voltage.

Connecting both incorrectly at the same time may or may not cause problems. There are 2 ways of doing that, with the ammeter (replacing the voltmeter) across just the load, or across both the load and the other meter (voltmeter connected as ammeter).

If the ammeter (replacing the voltmeter) is across just the load, the voltmeter (replacing the ammeter) will protect it. In this case the ammeter reads zero and the voltmeter reads the supply.

If the ammeter (replacing the voltmeter) is across the load and the other meter, then the ammeter will go up in smoke as above, unless a fuse or breaker goes first.

Answer 3

You will ruin the meter movement.

: )

Answer 4

If you connect an ammeter across the lines, a short -circuit results and your line acb will trip or fuses will be busted and when the voltmeter is connected in series with one line, its high resistance will cause a no current flow through the original circuit.

Answer 5

The normal current of the circuit would be restricted by the voltmeter in series.  It usually measures in parallel with high resistance to minimise the voltage drop over the meter itself.  If the lamp lights at all I'd be surprised.  The ammeter connected in parallel is another issue.  It has a low resistance and might cause an abnormally high current flow through itself and blow an internal protective device.

The reading would also be grossly incorrect and to utilise P=V x I, your answer for power consumed by the circuit would not be right;  if you were able to get an answer due to blown meters.