Volt
V
= E/Q 1 Volt = 1 Joule / 1
Coulomb
1. Calculate
the potential difference across a bulb if 20 C transfers 4 J of electrical
energy.
V = 4
J /20 C = 0.2 V
2. Calculate
the emf across a dynamo if 600 J of energy is transferred by 25 C of charge.
V =
600 J / 25 C = 24 V
3. A
bulb has a potential difference of 6V across it. Calculate the energy is
transferred by 90 C.
E = V
x Q = 6 V x 90 C = 540 J
4. A
train motor operates on a potential difference of 25 kV .Calculate the charge
that transfers 800 kJ of electrical
energy.
Q = E
/ V = 800000 J / 25000 V = 32 C
5. A
torch bulb runs off a cell of emf 1.5V Calculate the energy transferred by a
charge of 0.27 C
E = V
x Q = 1.5 V x 0.27 C = 0.41 J
A bulb takes a current of 0.25
A. How many Coulombs per second? 0.25 C per second
It transfers 60W of powerHow many Joules per second? . 60
J per second
Calculate
the emf of the supply. V = E ÷ Q = 60 / 0.25 = 240 V
