Unit 2 Flashcards
What effect does a higher capacitance have on the rate of charge/discharge
- increases time taken to charge
- longer for charge to build up on plates
Explain forward bias in terms of bands
- voltage from supply lowers energy of conduction band
- raises energy of valence band
- less work is done
What is e.m.f
The work done in moving each coulomb of charge in the circuit
What is a.c
Alternating current
- negative charges move back and forth
- changes direction
What happens if the timebase is halved
There will be have as many waves as before on the screen
When is a Wheatstone bridge circuit balanced
When the voltmeter reads zero
When is a Wheatstone bridge circuit out-of-balance
When the voltmeter doesn’t read zero
What band is full in an insulator
Valance band (lower band)
How can a diode be reversed biased
N-type connected to positive terminals. No conduction occurs
How can a diode be forward biased
N-type connected to negative terminals. Conduction occurs
What is added to give a p-type
Indium
What is added to give a n-type
Arsenic
What is a semiconductor
Insulating material that has been doped with an impurity to increase its conductivity
What effect will heating a semiconductor have
Resistance will decrease
What effect does a higher resistance have on the rate of charge/discharge
- increases time taken to charge
- decreases current
- decreases rate at which charges flow onto capacitor plates
Draw a graph of current against time for charging/discharging
(See notes for graph)
If resistance is increased across a resistor, what happens to the voltage and the current in the resistor
- voltage increases
- current decreases
How would internal resistance and e.m.f be found from a voltage/current graph
Gradient = -r Y-intercept = e.m.f