2. Electricity (required practical 4 - current/pd characteristics) Flashcards
1
Q
What is the practical?
A
investigating the current/voltage characteristics of circuit components
2
Q
What are the steps for the practical using a resistor?
A
- Use the voltmeter to read the potential difference across the resistor
- Use the ammeter to read the current through the resistor and record these values in a table
- Adjust the variable resistor and record the new readings on the voltmeter and the ammeter
- Switch the direction of the battery
- Take several readings of the potential difference and the current
- Plot a graph of current against the potential difference for a resistor
3
Q
What does switching the direction of the battery do for the resistor experiment?
A
- it means that the direction of the potential difference has now reversed
- the voltmeter and ammeter should have negative values
4
Q
What are the steps for the practical using a filament lamp?
A
- Use the voltmeter to read the potential difference across the filament lamp
- Use the ammeter to read the current through the filament lamp and record these values in a table
- Adjust the variable resistor and record the new readings on the voltmeter and the ammeter
- Switch the direction of the battery
- Take several readings of the potential difference and the current
- Plot a graph of current against the potential difference for a filament lamp
5
Q
What are the steps for the practical using a diode?
A
- Set up a series circuit including an extra resistor and milliammeter
- Adjust the variable resistor a number of times and record the potential difference and the current
- Do this with the battery in the forward and backwards direction
- Plot a graph of current against the potential difference for a diode
6
Q
Why is there an extra resistor in the circuit for the diode?
A
Because diodes are very easily damaged by a high current, so the extra resistor will keep the current relatively low, protecting the diode
7
Q
Why is a milliammeter needed in the circuit for a diode?
A
because the current will be very low, a very sensitive ammeter, milliammeter is needed