physics - IV characteristics

Question 1

outline the steps of the practical:

Answer 1

• set up circuit with lamp/resistor/diode
• alter the potential difference in regular increments
• record the current for each p.d
• plot a graph and repeat for other two components

Question 2

what component is required to alter the potential difference if your not using a variable power pack?

Answer 2

A rheostat, or variable resistor

Question 3

what is an Ohmic conductor?

Answer 3

• a conductor for which current and potential difference are directly proportional
• resistance remains constant as current changes
• temperature must be constant

Question 4

what must also be present in the circuit when testing the diode?

Answer 4

a protective resistor should be connected to prevent the current levels getting too high ~ it should be connected in series with the diode

Question 5

for which component does the polarity of the power supply matter and why?

Answer 5

the diode, since it only allows current to flow through in one direction

Question 6

what should be kept constant to get reliable results? How do you achieve this?

Answer 6

temperature should be constant ~ disconnect the power supply when not taking readings to avoid unnecessary heating

Question 7

what would you expect the I-V graph of a resistor to look like?

Answer 7

Straight line through the origin

Question 8

what would you expect the I-V graph of a diode to look like?

Answer 8

Like an exponentially increasing gepah

Question 9

What would you expect the I-V graph of a filament bulb to look like?

Answer 9

Like a cubic graph

Question 10

what happens to the resistance of a filament lamp as the temperature increases?

Answer 10

• resistance increases
• ions in metal have more energy, so vibrate more, causing more collisions and so a greater resistance