The volt

 

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

6.       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