Unit 3- MR OLDFIELD'S WORK

Write a Hypothesis for..

“Investigate how the resistance of the filament of the lamp changes as the current in the filament changes”

As the current in the filament lamp increases, the resistance of the filament lamp also increases.

• This is because as more current flows through the lamp, the filament heats up

• and causes metal atoms to vibrate more,

• so its harder for electrons to pass through

Write a method for…

“Investigate how the resistance of the filament of the lamp changes as the current in the filament changes”

1. Connect power supply, ammeter + filament in a single series loop. Connect voltmeter in parallel across filament lamp

2. Set power supply to the lowest voltage setting such as 1v, then switch on power supply

3. Read and record current from ammeter and potential difference from voltmeter, increase the voltage by small regular intervals such as in 1v steps; up to the maximum rating of the bulb such as 12v.

4. Record the readings of voltage and current at each steps

5. Switch off circuit for 30 secs in between readings to prevent lamp and wires from overheating

6. Repeat the entire process 3 times and calculate the mean current for each voltage, reducing the effect of random errors

Write a Hypothesis for..

“Investigate the relationship between temperature and the resistance of a thermistor”

• As the temp increases, resistance of thermistor decreases

• Higher temp provides more energy to the semiconductor material + releases more electrons

• Makes it easier for electric current to flow and results to lower resistance

Write a Hypothesis for..

“Investigate relationship between intensity of light and resistance of light dependant resistor”

• As the light intensity increases, resistance of the LDR decreases

• This is due to more light energy releases more charge carriers so its easier for electrons to flow

Write a Hypothesis for..

“Investigate the relationship between length and resistance of a wire”

• As the length of the wire increases, resistance of wire increases

• This is bc electrons must travel a long distance, leading to more collisions with atoms so makes it harder to flow

Write a Hypothesis for..

“Investigate the relationship between the diameter and resistance of a wire at constant temperature”

• As the diameter of the wire increases, the resistance of the wire decreases.

• This is bc a thicker wire provides a larger area for electrons to move through less collisions

• Makes current flow more easily

Write a Hypothesis for..

“Investigate the relationship between voltage and current in a diode”

• In forward direction, current increases as voltage increases; in reverse direction, no current flows

• Diodes are made to act like a one-way valve, allowing charge carriers to move in one direction

• While blocking them in the opp direction

Write a Hypothesis for..

“Investigate the relationship between number of lamps in series and total resistance”

• As the number of lamps in series increases, the total resistance of the circuit increases

• This is bc in a series circuit, total resistance is the sum of all components

• Each additional lamp adds another obstacle for the current to flow through

Write a Hypothesis for..

“Investigate the relationship between the number of lamps in parallel and total resistance”

• As the number of lamps in parallel increases, the total resistance of the circuit decreases

• This is bc adding parallel branches creates more paths for current to take

• This increases the total current + lowers the overall resistance of the circuit