Topic Menu

Cyber-chess a chess instruction site

Questions on Characteristic Curves - Filament Lamp

Q3.

(a) Draw, on the axes below, the current/voltage characteristic for a filament lamp. Do not insert any values for current or voltage.

    correct curve in positive quadrant

    correct curve in negative quadrant

    passing through origin

(3 marks)

(b) Explain why the characteristic has the shape you have drawn.

The current heats the filament making the temperature rise.

Resistance of a wire increases with temperature but p.d. and current do not increase proportionally.

It does not matter which way round you connect a filament lamp in a circuit therefore current passing through it in the opposite direction has the same effect - producing the same shape of characteristic in the negative quadrant.

(Max 3)

(c) The current/voltage characteristic of a filament lamp is to be determined using a datalogger, the data then being fed into a computer to give a visual display of the characteristic. Draw the circuit diagram required for such an experiment and state what is varied so as to produce a range of values.

Circuit diagram marks:

battery, variable resistance (or variable supply) and filament

current sensor in series circuit

voltage sensor across filament

the two sensor boxes connected to datalogger

Method marks:
The variable resistor or variable supply voltage is altered for each reading
thus changing both V and I

(5 max)
(Total 11 marks)