Simple circuits

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Question 29
Medium

A commercial electric deep-fryer is used in a restaurant kitchen to heat cooking oil.

a.

The deep-fryer is plugged into the mains supply and turned on. Explain why the temperature of the oil increases. Write about energy stores in your answer.

[2]
b.

The temperature of the oil increases from 20∘C20^\circ\text{C}20∘C to 180∘C180^\circ\text{C}180∘C. The mass of the oil is 4.0 kg4.0\text{ kg}4.0 kg. The specific heat capacity of the oil is 2100 J/kg∘C2100\text{ J/kg}^\circ\text{C}2100 J/kg∘C.

Calculate the energy required to increase the temperature of the oil. Use the equation:

change in thermal energy=mass×specific heat capacity×change in temperature \text{change in thermal energy} = \text{mass} \times \text{specific heat capacity} \times \text{change in temperature} change in thermal energy=mass×specific heat capacity×change in temperature
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c.

The power of the deep-fryer is 3000 W3000\text{ W}3000 W. The potential difference of the mains supply is 240 V240\text{ V}240 V.

Calculate the current in the heating element of the deep-fryer. Use the equation:

power=potential difference×current \text{power} = \text{potential difference} \times \text{current} power=potential difference×current
[3]
d.

A chef suggests, 'We should use a heating element designed to draw a higher current.' Suggest two reasons why this is a good idea.

[2]
e.

The deep-fryer has an outer casing made of stainless steel (metal).

Which wire(s) should be connected in the electric plug of the deep-fryer? Select all that apply:

  • Earth wire
  • Live wire
  • Neutral wire
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Simple circuits Questions

  1. GCSE
  2. /Physics
  3. /Simple circuits