Practise Edexcel IGCSE Physics observations, measurements and variables by reading instruments, presenting data and identifying investigation variables.
Diagram 1 shows the apparatus a student uses to investigate the bending of a wooden strip.
Part of the wooden strip is clamped to a table.
A load is fixed to the free end of the wooden strip, causing it to bend.
Diagram 1
The free end of the wooden strip is positioned a length, L , beyond the edge of the table, as shown in diagram 1.
The weight of the load causes the end of the wooden strip to move down through a height, h.
A student investigates how the length, L , affects the height, h .
This is the student's method for the investigation.
- clamp the wooden strip so that
- fix the load to the end of the wooden strip, as shown in diagram 1
- measure the height, h
The student repeats this method for different values of L.
Give the independent and dependent variables in the investigation.
independent variable
dependent variable
Give two control variables in the investigation.
1
2
Suggest how the student could accurately measure the height, h .
A student uses this apparatus to investigate how the efficiency of an electric motor varies with its input voltage.
This is the student's method.
- connect the electric motor to a d.c. power supply and a joulemeter
- attach a 1.0 kg mass to the electric motor using a length of string
- set the voltage of the power supply to 10 V and switch on the power supply
- switch off the power supply when the mass has been lifted through a distance of 50 cm
- record the input energy to the motor from the joulemeter
- calculate the energy transferred to the gravitational store of the mass
- calculate the efficiency of the motor
The student repeats this process, setting the power supply to a different voltage each time.
Give two control variables for the investigation.
1
2
This question is about waves.
A student uses a microwave source and a receiver to investigate microwaves.
Photograph 1 shows how the student sets up their apparatus.
Photograph 1
The meter shows the strength of the microwaves detected by the receiver.
The strength of the microwaves is measured in arbitrary units.
The student varies the distance between the microwave source and the receiver, and records the meter readings.
Photograph 2 shows the analogue meter for one of the readings.
Photograph 2
Give the reading on the analogue meter.
reading = arbitrary units