Required Practicals

Question 1

Give the equipment of the “Testing Insulators” required practical.

Answer 1

• Glass beaker
• Water
• Thermometer
• Assorted materials to insulate the beaker (e.g. bubble wrap or newspaper)

Question 2

Give the independent variable of the “Testing Insulators” required practical.

Answer 2

Material placed over the glass beaker (the INSULATOR)

Question 3

Give the dependent variable of the “Testing Insulators” required practical.

Answer 3

Temperature - thermometer MEASURES how well the material maintains the temperature.

Question 4

Give one control variable of the “Testing Insulators” required practical.

Answer 4

• The start temperature of the water
• The thickness of the glass beaker
• The thickness of the insulators/ the number of times the insulator has been wrapped around the beaker.

Question 5

Give the method of the “Resistance of an Adjustable Wire” required practical.

Answer 5

Step 1: Set up the equipment (series circuit with voltmeter, ammeter and an adjustable wire added)
Step 2: Start the length of the wire at 20cm and work up at regular intervals to 100cm. Measure the voltage and current at every point.
Step 3: Use Ohm’s Law to calculate resistance.

Question 6

Give some safety hazards in the “Resistance of an Adjustable Wire” required practical.

Answer 6

• Turn off electricity at every point where the wire is lengthened, to avoid overdose of energy or a fire hazard.
• Tie hair back
• Science goggles

Question 7

How should the results of the “Resistance of an Adjustable Wire” required practical appear on a graph?

Answer 7

Linear - /

Question 8

Describe the aim of the “IV Characteristics” required practical.

Answer 8

To describe the relationship between current and voltage because of an electrical component (e.g. resistor, bulb and diode) and how this shows them to be an ohmic or non ohmic conductor using graphs.

Question 9

Give the independent variable of the “IV Characteristics” required practical.

Answer 9

The component that we place in the circuit.

Question 10

Give the dependent variable of the “IV Characteristics” required practical.

Answer 10

Current and voltage , though voltage is measure in a scale.

Question 11

Give multiple control variables of the “IV Characteristics” required practical.

Answer 11

• The scale the voltage is changed to using the variable resistor
• The number of readings taken when the current/voltage is positive/negative
• The voltage of the battery
• The thickness of the wires
• The length of the wires
• The length of time the ‘component’ is connected to the circuit (temperature could become an obstacle)

Question 12

Why is a variable resistor included in the “IV Characteristics” required practical?

Answer 12

It is used to change the voltage on a regular scale (e.g. 0.1A, 0.2A) so we can measure the current and compare the results on a graph to determine whether the component is an ohmic or non ohmic conductor.

Question 13

True or False - You can change ONLY the current in order to receive valid results for the “IV Characteristics” required practical.

Answer 13

False - you can ONLY change the voltage, not the current.

Question 14

Why can you only change the voltage in the “IV Characteristics” required practical?

Answer 14

The voltage is measured in equal intervals as it is always on the x axis in Ohmic Conductor graphs.
I don’t know why this is, but it’s just one of those things to remember.

Question 15

In the “IV Characteristics” required practical, why is the resistance constant in the ‘Fixed Resistor’ section?

Answer 15

Because the voltage and the current are directly proportional, we can use Ohm’s law to show how resistance stays constant. As voltage and current are directly proportional, if one amount increases, so does the other by the same amount (like a scale factor) so the resistance is constant.
E.g. 
R=V/I
V = 4Vx2 = 8V
I = 2Ax2 = 4V
4/2=8/4 so resistance is constant.