Force, Energy & Communication - PowerPoint PPT Presentation

Force, Energy & Communication

Lesson 5

• To consolidate our knowledge on electrical power from last lesson
• To look at the costing for electricity
• To investigate the magnetic effect of a current

Charge passed = Current X Time

(coulombs) (amperes) (seconds)

Q = I t

Electrical power = Current X Voltage

(watts) (amps) (volts)

P = I V

cost of electricity = power (kW) x time (h)

x cost of 1kWh

energy

twice

energy

voltage

previous

subtract

To find the number of units used on an electricity bill, ………….. the …………… meter reading from the present one. You pay for the …………. you have used not the ………….. or the current supplied. If a label on an appliance says “1kWh” it means it will use ………….. at the rate of 1000 …………… per second . A “2kW” appliance uses energy …………….. as quickly as a “1kW” appliance.

• When a current flows through a wire held between two poles of a magnet there is an upwards force on it.

• The force becomes stronger if…
• the current is increased
• a stronger magnet is used
• there is a greater length of wire in the magnetic field

• The force isn’t always upwards .
• It depends on the current and the field directions.
• If the wire is in line with the field, there isn’t any force at all.

• To consolidate our knowledge on electrical power from last lesson
• To look at the costing for electricity
• To investigate the magnetic effect of a current