Paper 1 Flashcards
Explain why connecting the Earth wire to a metal case of a plug is Safe
Because if the live wire touches the metal case then the current will flow through the Earth wire rather than the human touching the case because the Earth wire has a lower resistance on the human
Hey student investigated how the resistance of a piece of wire varies with length in a circuit with a variable resistance explain why the student needed to adjust a variable resistor each time she change the length of the wire
A variable resistor changes the resistance of the circuit so it keeps the current the same for each length of wire so that the temperature of the wire is constant
Why does 1 kg of a gas have much larger volume down 1 kg of a solid
Particles in a solid have strong forces of attraction which allows them to have a fit structure however particles in a gas have negligible forces therefore the particles are far apart and they are more likely to take up more space
Explain why the total positive charge in an atom of an element is always the same
Protons gives the nucleus a positive charge and the number of protons of every atom of the same element is the same
Explain how a cavity wall reduces unwanted energy transfers
Cavity wall has two or more layers therefore it has a low thermal conductivity so the energy transferred by conduction is reduced
Explain the energy stores of a boiler that has a fuel cold water and a hot exhaust gas
Chemical energy store of the fuel reduces and energy transferred to the thermal energy store of the water and the air heating up the surroundings
Explain how a reading on a circuit of ammeters and voltmeters changes as environmental conditions change on a circuit containing an LDR
Resistance of the LDR changes when the light intensity changes. As light intensity Increases the resistance of the LDR decreases therefore the overall resistance in the circuit decreases.
This means that the current reading on the ammeter will increase as the overall current increases in the circuit. And the potential difference across the LDR will therefore decrease so the reading on the voltmeter will also decrease
How should a student change a circuit to give negative values for current and pd
Reverse the connections to the cell
The difference between direct and alternating potential difference
Direct potential difference is always in the same direction however alternating potential difference changes direction
Explain why it is better to use a cable with do you know resistance when connecting to a car
No resistance means high currents therefore the battery of the car charges faster
A student increases the temperature of a thermistor explain how the current in the thermostat changed
Current increased as resistance decreased
Switch closes in the circuit containing a lamp how will the potential difference across the lamp change after the switch is closed
Potential difference across the lamp will increase as the current will increase because the circuit is complete
Explain why the temperature heating element increases in a kettle when it is connected to the mains supply
Electrons collide with particles in the heating element which increases the thermal energy of the particles
Explain Y on a graph the time taken for kettle to switch off does not go through the origin
Because the castle took time to heat up
Why is it difficult to detect gamma radiation
Gamma radiation can pass through any detector
Explain why a count rate detecting the activity of a radioactive substance is less than its actual activity
Radiation spreads in all directions and only some of the radiation that passes through passes through the Geiger-Müller tube is detected
Explain when handling a radioactive substance a teacher stood as far away as possible
So they reduce irradiation from the radioactive source as it eradication increases risk of cancer
Why would it be safe person to touch a metal case when the live wire has touched the case
The current flow through the Earth wire as the resistance of the Earth wire is lower than the resistance of the person
The temperature of water stays constant even though it is continued to be heated why
Energy is dissipated to the surroundings at the same rate that energy is transferred to the water therefore it cannot increase in temperature
What is the motion of the particles in solid ice cream
They vibrate about in fixed positions
When a liquid is called and frozen what happens to the kinetic and potential energy of the particles
Both decrease
Explain the property a liquid coolant should have
A high specific heat capacity so it can absorb more energy with only a small temperature decrease
ANB are both radioactive sources source a has a longer half life than B what does this mean
The nuclei in source A are more stabler
Explain why a kangaroo can jump higher as speed increases
Because the max extension increases therefore elastic potential energy also increases this is transferred to the gravitational potential energy
Explain why spark detector cannot detect beta radiation as a spark detector works by alpha particles ionising atoms
Bator radiation is weekly ionising
Compare the reading of an ammenter on a circuit with a resistor to a circuit with a resistor and another resistor added in parallel
The reading on the parallel circuit would be twice the reading on the normal circuit
What name is given to the energy needed to change the state of a liquid
Specific latent heat of fusion
Explain why a company that claims they have an efficiency of 400% for a heat pump is not correct
Efficiency must be lower than 100% as energy dissipate into the surroundings
What is the function of a fuse
L protects electrical device if current is greater than value of fuse the fuse will melt and break the circuit
What is the function of a fuse
L protects electrical device if current is greater than value of fuse the fuse will melt and break the circuit
What are the properties of a radioactive source for a medical equipment
There should be a short half-life there should also be so there is less damage to cells a low ionising power
How does increasing the resistance in a circuit affect the brightness of a lamp
Increasing resistance will decrease current therefore the lamp will be dimmer
Why was having a more efficient motor increase the speed of a car
A lower proportion of wasted energy therefore there is a higher proportion of energy that is converted into kinetic energy
What is gamma radiation
Electromagnetic radiation from the nucleus
Why is gamma emitters used for x-rays
Gamma radiation is the most penetrating therefore most of the radiation emitted will leave the body and therefore it can be easily detected outside the body
What is the meaning for the term half life
The time taken for the number of nuclei of the isotope in a sample to half
Describe the hazard course of a radioactive substance that has a short half life
Initially there will be a high hazard however the level of hazard will drop quickly due to the short half life
Why is a radiated equipment not hazardous
They do not become radioactive
How may the electrons distance from the nucleus increase or decrease
The distance will increase when they absorb electromagnetic radiation and the distance will decrease when they emit electromagnetic radiation
Explain and compare two different types of radioactive decay causes transmutation which is the process of an element changing into another
Beta decay
Atomic number will increase by one when a neutron decays into a proton
Alpha decay
Atomic number will decrease by two when an alpha particle is emitted from the nucleus
Both change the number of protons in nucleus
Explain why a value for specific heat capacity of water is greater than predicted value
Some of the energy supplied will not be used to raise the temperature of water
Why is heating a gas increases the speed of gas particles
will increase the temperature of the gas particles and temperature is proportional to kinetic energy and when kinetic energy increases speed increases
Explain why mass of Geseous water with the same temperature of a mass of liquid water has more energy
Gassiest water requires more energy as it is needed to change the state of water and break the bonds
