Graphs

Question 1

How to investigate Current-Voltage?

Answer 1

-Use a variable resistor to allow the potential difference to cross the component and the current
-Repeat and take averages

Question 2

What is the I-V characteristic for a metallic conductor?

Answer 2

-At constant temperature, is directly proportional
-Resistance doesn’t change as it is straight through the origin
-The shallower the gradient, the greater the resistance
-Metallic conductors are ohmic

Question 3

What is the I-V characteristic for a filament lamp?

Answer 3

-Is a curve, which starts steep but gets shallower as the P.D rises
-The filament is a coiled up length of metal wire
-Current flowing through increases the temperature, so the resistance increases

Question 4

What is a thermistor?

Answer 4

-NTC or Negative Temperature Coefficient, which means the resistance decreases as the temperature goes up
-An I-V characteristic shows that as current increases so does temperature so gets steeper as there is less resistance
-Warming, gives more electrons energy to escape from their atoms, which means there are more charge carriers available, so current increases

Question 5

What is an LDR?

Answer 5

-A light dependent resistor, the greater the light intensity, the lower the resistance
-Light provides the energy that releases more electrons, which means more charge carriers, which means a higher current and a lower resistance

Question 6

What is a diode?

Answer 6

-Are designed to let current flow in one direction only
-Forward bias is the direction the current is allowed to flow, the direction of the arrow in the symbol
-Most diodes require a threshold voltage of about 0.6V before they will conduct
-In reverse bias, the resistance of the diode is very high and the current which flows is very tiny