current,potential difference and resistance

Question 1

draw the circuit symbol for a cell

Question 2

draw the circuit symbol for battery

Question 3

draw the circuit symbol for a lamp

Question 4

draw the ciruit symbol for a fuse

Question 5

draw the circuit symbol for a voltmeter

Question 6

draw the circuit symbol for an ammeter

Question 7

draw the circuit symbol for an diode

Question 8

draw the circuit symbol for a resistor

Question 9

draw the circuit symbol for a thermistor

Question 10

draw the circuit symbol for a variable resistor

Question 11

draw the circuit symbol for the LDR

Question 12

draw a circuit symbol for an LED

Question 13

what is electric current

Answer 13

the flow of electrical charge

Question 14

state the equation linking charge,current and time

Answer 14

Q= l t

charge-couloumbs
current-amperes
time-seconds

Question 15

what can be said about the value of current at any point, in a single closed loop

Answer 15

current is the same at all points in a closed loop

Question 16

what 2 factors does the current in a circuit depend on

Answer 16

.potential difference
.resistance

Question 17

what equatiom should be used to calculate potential difference if current and resistance are known

Answer 17

V= I R

potential difference= v
current= A
resistance= Q

Question 18

what is an ohmic conductor , state the condition required

Answer 18

. an conductor for which current and potential difference are directly proportional

.resistance remains constant as current changes

.temperature must be constant

Question 19

list 4 components for which resistance is not constant as current changes

Answer 19

. lamps
.diodes
.thermistors
.light dependant resistors LDRs

Question 20

what happenens to the reistance of a filament lamp as the temperature increases, why

Answer 20

. resistance increases

.ions in metal have more energy,so vibrate more causing more collisions with electrons as they flow through the metal,creating greater resistance to current flow.

Question 21

what is different about current flow through a dioide

Answer 21

. the current only flows in one direction

.resistance is very high in the other direction,preventing current flow

Question 22

state what happens to the reistance of a thermometer as temperature increases

Answer 22

the thermometers resistance decreases

Question 23

give 2 examples of when a thermister may be used

Answer 23

. in a thermostat , to turn a heater on below a certain temperature

. in a freezer to turn on a cooler when the temperature becomes to high

Question 24

state what happens to the reistsnce of LDR , as the light intensity decreases

Answer 24

the ldrs resistance increases

Question 25

give an application for a ldr

Answer 25

. street lights often use ldrs

.when light levels become too low,the light gains sufficient current to turn on