Wrong Answers From Multiple Choice Flashcards
When doing moments, where do you measure everything to?
The same pivot - point
When doing any calculation with a car speeding up or slowing down, what should you work out first?
The net resultant force
In terms of radiation, what type is transferred and what qualities does colour black have?
Gains infra-red radiation and black is best absorbed and emitted
When doing any refraction/reflection question, what should you always look for first?
The position of the normal - check where it is to find where ray strikes it at a particular angle
How does current effect the resistance of filament lamp?
Filament lamp has more resistance as more current is passed through because the temperature rises
How do you rectify a current in a circuit that uses an AC power supply, two diodes and a lamp?
Set up power supply and lamp as normal and then place each diode either side of lamp with each diode having its tip (pointing towards) the same direction.
When shown a magnetic field going into a page and a beam of electrons or beta particles entering to the right, what should you use to work out the force and where would it be?
Use Fleming’s left hand rule!
REMEMBER that beta particles/electrons are not the conventional current so when using the left hand rule, put finger for current the other direction to the beta particle movement (the left) because that would be the conventional current.
The force would be down the page.
What happens to atomic structure during beta decay?
A neutron from nucleus changes into a proton, electron and (an uncharged massless relative of electron called antineutrino).
Remember that the mass number will not change as for the neutron that has been lost, a proton has been absorbed.
Describe the fall of an object to Earth that is affected by air resistance which eventually reaches a constant value? (In terms of acceleration/deceleration)
It has decreasing acceleration (as air resistance-force upwards is increasing).
And then it has zero acceleration (as the object reaches terminal velocity - no change in speed)
Which of geothermal, oil, water held behind dam and wind energy are derived from the sun?
Just water held behind dam
In conduction, how is thermal energy transferred if one end of a copper rod is heated.
FREE ELECTRONS do the transferring. They transfer energy from hot end to cooler end.
What type of image is formed by a magnifying glass - how would it appear on a lens diagram.
Magnifying glass is a virtual image and the image is formed behind the original object (& lens) and a bigger version of it.
How to demagnetise a magnet and why does it work?
Heating makes electrons spin much more so demagnetised as for a magnet they need to point in one direction.
If magnet is hammered, it’s atomic magnets are moved out of line (same principle as heating).
Pulling it slowly from a coil carrying AC
In a potential divider, if light increases on a thermistor, how does voltmeter reading across thermistor and on normal resistor change?
Reading is lower on thermistor (as resistance decreases)
Reading is higher on normal resistor as total voltage across the PD must be equal so if thermistor reading goes down, then this goes up.
What did Rutherford’s experiment find and what did he send into atom?
He sent alpha particles because they have a positive charge. Most went through - which showed atom was hollow. Some bounced back which showed there was something stopping them. Some were deflected which showed that alpha particles were charged.
Ways to protect yourself from radiation?
Hold Source with tongs.
Wash hands after using.
In a manometer, how do you find the pressure of the gas supply?
Work out atmospheric pressure first (or work out from a barometer of they have already given you that).
Then add atmospheric pressure to the height difference of mercury level (height difference is basically the excess mercury).
What two feature affect sensitivity of thermometer.
Thickness of glass bulb - increase in thickness means increase sensitivity
Diameter of liquid thread - decrease in diameter means increase sensitivity
What equipment would you need to calculate specific heat capacity of copper if you already had a block of copper, an electric heater and knew the power of the heater?
A balance, A stopwatch (energy is power x time) , a thermometer
Describe the magnetic field in a transformer, first in the soft-iron core and then in the secondary coil.
In both soft-iron core and secondary coil, magnetic field is changing.
When dropping a ball onto the floor, how would you increase its speed by double just before hitting floors? (Ignore air resistance)
Drop the ball from FOUR times the height above the floor as acceleration is m/s SQUARED
So if speed is doubled then height needs to be speed squared.
Temperature of melting ice and boiling water??
Both constant
