P3

Question 1

Why does the temperature of something remain constant when it is under the sun sometimes?

Answer 1

Rate of energy absorbed by the sun will equal the rate of energy given out

Question 2

Describe the energy changes in a filament lamp?

Answer 2

Electrical energy transferred into light and heat energy

Light is the useful energy and heat is wasted energy

Question 3

3 ways of reducing heat loss in a building?

Answer 3

1. ) double glazing
2. )Thicker walls
3. )insulation of walls

Question 4

How can you reduce unwanted energy transfer in mechanical system

Answer 4

Reduce friction by lubricating moving parts

Question 5

How can you increase the efficiency of a system

Answer 5

Reduce waste energy ( insulation or lubrication)

Recycling waste energy

Question 6

Advantages of using nuclear power ?

Answer 6

A lot of energy per kg of fuel
no greenhouse gasses
Low fuel costs

Question 7

Social factors to consider for energy production?

Answer 7

Visual pollution

Sound pollution

Question 8

How is hydroelectric power produced?

Answer 8

When water is released from a dam it is used to turn a turbine
this turbine then turns a generator and produces energy

Question 9

Advantages of tidal energy ?

Answer 9

Relatively reliable as tides occur twice a day
cheap to run
no greenhouse gasses produced

Question 10

There is a plan to replace the existing transmission line from the windfarm with
one at the higher potential difference of 400 kV.
The new transmission line will cross more than 200 km of mountains.
The cables will hang 50 m above the ground from 600 new, taller pylons.
Eventually, about 1000 of the old, shorter pylons will be removed.
Discuss the advantages and disadvantages of this plan.

Answer 10

Social factors / economic factors
• people may not like it (NIMBY) / pressure groups
• cost arguments
Environmental factors
• spoiled view / risk of bird strike
• space for extra infrastructure eg. access roads / substations
Associated hazards
• danger from higher voltage
• dangers from construction work in mountainous area
• danger to maintenance crew from working at greater height
Energy efficiency arguments
• higher voltage leads to lower current
• lower current means reduced heat losses
• higher voltage means / lower current / can transmit energy
further
• reduced heat loss means improved efficiency
Logical use of data
• taller pylons can be seen from further away
• net reduction in number of pylons / need to remove old ones
• stronger materials needed for pylons / cables
• need for new transformers
Appropriate calculations
• 1000 - 600 = 400 fewer pylons (approx.)
• current reduced by a factor of 132/400 (0.33)