Current and PD and Charge Flashcards
What is an electric current?
An electric current is a flow of negative charge. (electrons)
What is current measured in?
Current is measured in amps (A) - using a ammeter
What is the equation for calculating current?
Current (I) = charge (Q) / time (T)
- Time measured in seconds
- Charge measured in coulombs
- Current measured in amperes
Calculate the charge that flows when a current of 0.25A flows for 2 minutes
Q=? I=0.25 T=120s (2×60=120)
Q = 0.25 × 120
Q = 30c
Calculate the current that flows when a charge of 4500c is transferred in flows for 3 minutes
Q=4500c I=? T=180s (3×60=180)
I = 4500 / 180
I = 25A
Calculate the time it takes for 600c to be transferred when a current of 12A flows
Q=600c I=12A T=?
T = 600c / 12A
T = 50s
Calculate the charge that flows when a current 0.38A flows for 55 seconds. Give your answer to 2 Significant Figures
Q=? I=0.38A T=55s
Q = 0.38 × 55
Q = 21(2sf.)
Calculate the current flowing when 9000c of charge flows through the lamp in 30 minutes
Q=9000c I=? T=1800s (30×60=1800)
I = 9000 / 1800
I = 5A
What is Potential Difference (PD) measured in?
It is measured in Volts (V)
What is the equation for calculating PD?
Potential Difference (PD) = Energy Transferred (Joules) / Charge (coulombs)
How much energy is transferred by a 6V bulb when 15c of charge passes through it ?
E=? V=6v Q=15c
E = 6 × 15
E = 90J
Calculate the Potential Difference over a device which transfers 5kJ of energy when 400c of charge passes through it?
E=5000J V=? Q =400c
V = 5000 / 400
V = 12.5v
1a) Calculate the current flowing when 9000c of charge flows through the lamp in 30 minutes?
1b) The charge does 54kJ of work as it flows through the lamp. Calculate the PD across the lamp
1a) Q=9000c I=? T=1800s
I = 9000 / 1800
I = 5A
1b) E=54,000J V=? Q=9000c
V = 54,000 / 9000
V = 6v
