Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
102 Cards in this Set
- Front
- Back
|
What is a scalar? |
Size only e.g. distance (m).
|
|
|
What part of the atom make up the nucleus? |
Protons and electrons. |
|
|
What charge do protons have? |
Positive. |
|
|
What charge do electrons have? |
Negative. |
|
|
How does an object gain a charge when rubbed? |
By a transfer of electrons. |
|
|
Positive charge is caused by an object losing/gaining electrons. |
Losing. |
|
|
Negative charge is caused by an object losing/gaining electrons. |
Gaining. |
|
|
Like charges attract/repel? |
Repel. |
|
|
Opposite charges attract/repel? |
Attract. |
|
|
Define current. |
The rate of flow of electrons . |
|
|
Define voltage. |
The energy per unit of charge. |
|
|
What is Ohms Law? |
The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor. |
|
|
The greater/lesser the vibrations, the greater/lesser the resistance. |
Greater, greater. |
|
|
Name the three rules of a series circuit. |
Current is the same throughout the circuit. P.d. of battery = sum of component voltages. Total resistance = sum of component resistances. |
|
|
Name the three rules of a parallel circuit. |
Current from the battery = sum of the current in each branch. Voltage is the same across each branch. Resistance is calculated using R=V/I |
|
|
What is direct current (D.C)? |
When the current flows in one direction. |
|
|
What is alternating current (A.C)? |
When the current direction repeatedly reverses. |
|
|
On an oscilloscope tracer what does the y-gain control (y-axis) show? |
The potential difference (voltage). |
|
|
On an oscilloscope tracer what does the time base control (x-axis) show? |
Time. |
|
|
What is a scalar? |
Size only e.g. distance. |
|
|
What is a vector? |
Size and direction e.g. velocity. |
|
|
On a distance-time graph, how do you work out the distance? |
Read from the y-axis. |
|
|
On a distance-time graph, how do you work out the speed? |
Gradient of the graph. |
|
|
On a distance-time graph, how do you know if the object has a constant speed? |
It will be a straight line. |
|
|
On a distance-time graph, how do you know if the object is accelerating? |
Curve with an increasing gradient. |
|
|
On a distance-time graph, how do you know if the object is decelerating? |
Curve with a decreasing gradient. |
|
|
On a distance-time graph, how do you work out the average speed? |
Total distance divided by total time. |
|
|
On a velocity-time graph, how do you work out the distance? |
The area under the graph. |
|
|
On a velocity-time graph, how do you work out the velocity? |
Read from the y-axis. |
|
|
On a velocity-time graph, how do you know if the object has a constant velocity? |
It will be a horizontal straight line. |
|
|
On a velocity-time graph, how do you if the object is accelerating? |
Upwards gradient. |
|
|
On a velocity-time graph, how do you know if the object is decelerating? |
Downwards gradient. |
|
|
On a velocity-time graph, how do you know if the object is going in the opposite direction? |
Negative velocity. |
|
|
On a velocity-time graph, how do you know if the object is at rest? |
Zero on the y-axis. |
|
|
What is Newton's 1st Law of Motion? |
- An object at rest will stay at rest - A moving object will keep moving at same speed & direction ..... unless acted on by a resultant force. |
|
|
Define resultant force. |
A single force that has the same effect as all the forces acting on it. |
|
|
When is the resultant force 0 newtons? |
If an object is stationary or moving at a constant speed. |
|
|
What is Newton's 2nd Law of Motion? |
F = m times a. |
|
|
The __________ the resultant force, the ________ the acceleration. |
Bigger, bigger. |
|
|
What is Newton's 3rd Law of Motion? |
When 2 objects interact, they always exert equal and opposite forces on each other. |
|
|
What is the equation for stopping distance? |
Thinking distance + braking distance. |
|
|
What is the braking distance? |
Distance travelled by the vehicle during the time the braking force acts. |
|
|
What is the difference between mass and weight? |
Mass is amount of matter in an object. Weight is the force acting on an object due to gravity. |
|
|
What is the gravitational field strength on earth? |
10m/s squared. |
|
|
What is terminal velocity? |
When the drag increases until it equals the weight. |
|
|
What is elastic potential energy? |
The energy stored in an elastic object when work done on it to change its shape. |
|
|
What is work done the same as? |
Energy transferred. |
|
|
What is the conservation of momentum in a closed system? |
total momentum before = total momentum after. |
|
|
How can impact force be reduced? |
By increasing the time of the impact. |
|
|
How do you work out the frequency of AC supply? |
Time for one cycle |
|
|
What is the unit for current? |
Amps, A. |
|
|
What is the unit for potential difference? |
Volts, V. |
|
|
What is the unit for resistance? |
Ohms, |
|
|
What is the unit for power? |
Watts, W. |
|
|
What is the unit for charge? |
Coulombs, C. |
|
|
What is the unit for energy? |
Joules, J. |
|
|
How does a fuse work? |
A thin wire that heats up and melts, breaking the circuit if the currents too large. |
|
|
How does a circuit breaker work? |
Its an electromagnetic switch that opens (trips) if the current is too large. |
|
|
How does a residual current circuit breaker (RCCB) work? |
Cuts off the current if the current in the live wire of an appliance is different to the neutral wire. |
|
|
What should you take into consideration when working out the cost effectiveness? |
Purchase cost, product lifetime, power, efficiency and disposal cost. |
|
|
What is a radioactive substance? |
It contains unstable nuclei that become stable by emitting radiation. |
|
|
What is a Geiger counter used for? How does it work? |
It is used to detect radiation. The counter clicks each time each time a radioactive particle is detected. |
|
|
What is radioactive activity? |
The number of atoms that decay per second. |
|
|
What is an isotope? |
An atom with the same number of protons but different number of neutrons. |
|
|
What is the half-life of a radioactive isotope? |
The average time it takes for the number of unstable nuclei to halve. |
|
|
Is alpha radiation more or less dangerous inside the body? Why? |
More dangerous inside the body as it is more ionising to cells. |
|
|
Name four uses of alpha, gamma and beta radiation. |
Medical tracers, radioactive dating, smoke alarms and tracing leaks in underground water pipes. |
|
|
What is the plum pudding model? |
Atom has no nucleus. Positively charged matter spread out evenly. Electrons buried in positive matter (like plums in a pudding). |
|
|
What is the symbol for alpha radiation? |
Alpha = |
|
|
What does an alpha particle consist of? |
2 protons & 2 neutrons. |
|
|
What is an alpha particles relative charge? |
+2 |
|
|
What is an alpha particles relative mass? |
+4 |
|
|
What is an alpha particles effect of electric field? |
Attracted to negative plate due to its positive charge. Deflection is small due to large mass. |
|
|
What is an alpha particles effect of magnetic field? |
Small deflection. |
|
|
An alpha particle is formed when.......... |
2 protons + 2 neutrons are emitted from a nucleus as an alpha particle. |
|
|
What is the effect of decay on an alpha particle's mass & proton number? |
Mass number down by 4. Proton number down by 2. |
|
|
What is the decay equation for an alpha particle? |
X |
|
|
What is alpha radiation absorbed by? |
Thin sheet of paper. |
|
|
List the three types of radiation in order of least to most in terms of penetration. |
Alpha, Beta and Gamma. |
|
|
List the three types of radiation in order of least to most in terms of ionisation. |
Gamma, Beta and Alpha. |
|
|
What is the symbol for beta radiation? |
Beta = |
|
|
What does a beta particle consist of? |
1 electron. |
|
|
What is a beta particles relative charge? |
-1 |
|
|
What is a beta particles relative mass? |
0.0005 |
|
|
What is a beta particles effect of electric field? |
Attracted to positive plate due to its negative charge. Large deflection due to small mass. |
|
|
What is a beta particles effect of magnetic field? |
Larger deflection in the opposite direction to alpha radiation. |
|
|
How is a beta particle formed? |
When the nucleus has too many neutrons. A neutron splits into a proton and an electron. The electron is emitted as a beta particle. |
|
|
What is the effect of decay on a beta particles mass & proton number? |
Mass number has no change. Proton number goes up by 1. |
|
|
What is a beta particles decay equation? |
X |
|
|
What is beta radiation absorbed by? |
Aluminium sheet (5mm thick). Lead sheet (2-3mm thick). |
|
|
What is the symbol for gamma radiation? |
Gamma = |
|
|
What does gamma radiation consist of? |
Its an E.M. wave. |
|
|
How is gamma radiation formed? |
Its emitted as an E.M. wave after an alpha or beta particle is emitted from the nucleus. |
|
|
What is gamma radiation absorbed by? |
Thick lead sheet (several cm thick). Concrete (1m). |
|
|
When does nuclear fission occur? |
When a neutron is fired at a nucleus of uranium-235 or plutonium-239. |
|
|
How does nuclear fission work? |
Nucleus splits to smaller fragments, releasing energy & 2 or 3 high speed neutrons. A chain reaction occurs as the released neutrons cause further fission reactions. |
|
|
What does a nuclear reactor contain? |
Fuel rods, control rods, water and a reactor core. |
|
|
What is nuclear fussion? |
The process of forcing 2 nuclei close enough together so they form a single larger nucleus. Occurs by making 2 light nuclei collide at high speed, releasing energy. |
|
|
Where does nuclear fusion occur? |
In the sun's core. |
|
|
Describe the birth of a star. |
-Stars form from clouds of dust and gas. -Gravity pulls the particles in the clouds together to form a protostar. -Protostar becomes denser and hotter, main sequence star is formed. |
|
|
Describe the life of a low mass main sequence star. |
-No more hydrogen nuclei to fuse together. -Swells and cools to a red giant. -Star collapses on itself due to gravity and heats up to form a white dwarf. -Eventually cools to a black dwarf. |
|
|
Describe the life of a high mass main sequence star. |
-No more hydrogen nuclei to fuse together. -Swells to a red super giant. -Collapsed red super giant explodes as a supernova. -The core will then turn in to a neutron star or if big enough a black hole.
|
