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Power of Electrical Appliances

• A moving charge transfers energy as the charge does work against the resistance of the circuit
• Electrical appliances transfer energy to components in the circuits when some current flows.
• No appliance transfers all energy usefully. Higher current = more energy transferred to the thermal energy stores of components
• Energy transferred depends on how long the appliance is on for and itspower .
• Power = energy transferred per second.
• More energy transferred in a given time = higher power
• Energy Transferred (J) = Power (W) X Time (s)
• E=Pt
• Appliances have power ratings (maximum safe power that it can operate at). They tell youmaximum amount of energy transferred between stores per second when appliance is in use = can compare models as lower power rating means less electricity an appliance uses, so cheaper to run.
• Higher power means transfers more energy but may not be more efficient. It may transfer a lot of the energy as wasted energy or transfer the same amount of energy usefully.

How long have you…? (present perfect 4) Exercises

Use the information given to create questions beginning with ‘How long…?’

• It is snowing.

• The weather is shining.

• John and Kate are married.

• My brother has gone on holiday.

• My aunty and uncle live in Canada.

• My sister is a teacher.

• I work at the chemist.

• I’ve known Susan since I was a baby.

• Jonathan is learning to speak to Mandarin.

Fill in the missing gaps in the sentences using the present perfect (=has/have + past participle)

• I have known Kate a long time.

• My brother has been playing the piano he was 11 years old.

• My mum and dad on holiday to America. They

gone since last Sunday.

• I Ben and Emma since primary school.

We to the same primary and secondary school.

• My sister learning to speak French because she
is going to France next month.

Use the appropriate words in the missing gaps.

have you lived       lives      to

has been       works        have known

I have bought       have worked.

• My sister in Spain. She is studying Spanish

with her friend Rosie. I Rosie since I was 5.

• Spencer like with Jamie. They have worked

together for 2 years.

• How long in Australia?

• a new dress for prom.

• He to Thorpe park.

Challenge: Create 4 of your own questions beginning with ‘How long……?’

1.

2.

3.

4.

1 2 3 4 5 6

“Every accomplishment starts
With the decision to try.” Gail Dever

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