# Higher Physics Unit 2

## 23 terms · Revision flashcards for SQA Higher Physics

### What happens to a charge in an electric field?

It experiences a force

Work is done

### What is the potential difference between 2 points?

The work done moving 1C of charge between the points

3V

1) W=QV
2) Ew=Fd
3)Ek=½mv²

### What is EMF ?

The energy supplied to each coulomb of charge passing through the source

### What are the main formula for EMF

1) E= V + Ir
2) E= I(R+r)
3) V=IR
4) lost volts = Ir

### What is an open circuit?

1) A source of EMF connected only to a voltmeter
2) As there is no current there are no lost volts
3) The voltmeter can read the actual EMF

### What are lost volts?

Voltage across the internal resistance

### What is terminal pd?

The voltage actually available at the output of a supply

### What is a load resistor?

Any external resistance

### What is a short circuit current?

1) When there is no external resistance R=0
2) Current = EMF÷internal resistance
(I=E÷r)

Zero

### What is Capacitance?

How much charge can be stored per volt
(C=Q÷V)

### What is the relationship between the charges stored on 2 plates and the voltage between them?

Directly proportional
As on increases so does the other
(Q=CV)

### What is the effect of frequency on resistors and capacitors?

No effect on resistors
Capacitors - current increases with frequency

### What effect do capacitors have on d.c and a.c signals?

Allows a.c to pass
Blocks d.c

### What are op-amps used for?

Increase the voltage of a signal

### For an ideal op-amp what is the condition for current?

Infinite input resistance
No input current

### For an ideal op-amp what is the condition for voltage?

No pd between the input terminals
Both input terminals at the same pd

Inverting Mode

### What type of op-amp amplifies the difference between the inputs?

Differential Mode

### When do op-amps become saturated?

When the maximum values of it's power supply have been reached