Here are some quick questions to help you test your knowledge for GCSE physics paper 1 for AQA. If you haven't seen the full video going through everything you need to know for the paper yet, it's worth watching that first. Link is in the description. You'll probably want to pause the video for any calculation questions here. Oh, and you'll need a calculator, too. Let's go. Question one. What is the kinetic energy equation in symbol form? Also, rearrange it to make V the subject. Even though you probably won't have to remember equations because they'll be in the formula sheet, people who remember the equations do better. The equation is E=/ MV ^2. That's kinetic energy equals a half * mass in kilg* speed squar in m/s rearranged v equ= the square<unk> of 2 e over m. Question two, what is the equation for gravitational potential energy gp? And how high off the ground is a 500 g ball if it has 100 jewels of GPE? Let's say that G gravitational field strength is 10 in this [Music] case. The equation is E= MGH. GP equals mass in kilog time gravitational field strength or G. You might just say gravity as well time height in meters. Rearranging for H, we get E / M * G. So 100 / 0.5 * 10. Did you remember to convert grams to kilograms? 500 divided by 1,000 is 0.5. So, it's 0.5 kg. Don't forget that when you're dividing by two things on the bottom, you must use the fraction button on your calculator or use brackets around the two numbers. Question three, what is the definition of power? And how much energy does a 5 W light bulb use in an hour? Power is the rate of energy transferred or rate of work done. Work done is just another fancy term for energy transferred. Any rate is something divided by time. So power equals energy divided by time. P equals E / T. Rearranging to make energy the subject, we get P * T. So 5 * 3,600 is 18,000 JW or 18 kJ. The 3,600 is just 1 hour in seconds, which is what it has to be in order to go into the equation. Question four. The 5 W light bulb only emits 3 W of light. What is its efficiency as a decimal and percentage? Efficiency is just a ratio of useful energy out divided by total energy in. This gives us 0.6 as a decimal. Multiply it by 100 and it turns into a percentage 60%. Question five. The equation for current is I= Q / T. Or you might see a rearranged version Q= it in your formula sheet already. What are the units for current I and charge Q? Current is measured in ampairs. Usually we just say amps for short, but we just write a. Charge is measured in kulum. They're groups of electrons essentially. Current tells us the rate of flow of charge in kulum per second. So a current of 10 amps say means that 10 kulum are passing every second. Question six. What is Ohm's law and how can it be used to find the resistance of this resistor from its graph. Ohm's law is V= IR voltage or the balls prefer you to say potential difference or PD that's measured in volts. That's equal to current in amps time resistance in ohms. Rearranging we get R= V / I. So we just pick a nice point on the line on the graph and divide the PD by the current. You'll get the same answer no matter what point you pick, but only if it's a straight line. By the way, this shows that this has a constant resistance. So we can say that it's an omic resistor. Question seven. The graph for a filament bulb is not a straight line. Why is that? As the filament in a bulb is made of metal that consists of an ionic latice surrounded by free electrons. The higher the current, the hotter the metal gets and the more these ions vibrate. This makes it harder for the electrons to flow as they collide more frequently with the ions. That means the resistance gets higher at larger currents. That's why the graph is curved. But just remember that if you want to calculate the resistance from this graph, you always pick a point. You never draw a tangent on this graph ever. Question eight. What is true for electrical components in series and parallel? Bonus points if you can find the missing numbers. components say resistors in series will have the same current for the total PD will be shared between them. If the resistances are the same, this PD is shared equally. If not, the larger resistor gets the larger share of the PD. So you can hopefully see that the 12 volts total here will get split into 8 volts and 4 volts according to the resistances. Components in parallel have the same PD or rather their branches do we should say. It's the current that's shared this time. So there must be 0.4 amps flowing in the bottom branch using V= IR. The missing resistance must be equal to 12 volt divided by 0.4 amp. That's equal to 30 ohms. Electricity questions pretty much always come down to this using your knowledge of series and parallel circuits with Ohm's law. Question nine, what are thermostatrers and LDRs and what do they do? Their special resistors, their resistance changes. Thermisters resistance will decrease if the temperature gets hotter. And so that means resistance will of course increase if the temperature goes down. It's kind of the opposite to a metal filament in that regard. An LDR is a light dependent resistor. It works in a similar way to a thermostat, but just that this time it's an increase in light intensity that causes the resistance to go down. Question 10. What is the voltage and frequency of UK mains electricity? And how is AC different to DC? Main's voltage here in the UK is 230 volt and its frequency is 50 Hz. It's AC, alternating current, sometimes called alternating PD. The current and PD reverse direction so many times a second. DC is direct current or direct PD. The current and PD do not change direction. That's what you get out of batteries, for example. Question 11. What fuse would you need in the plug of a 2 kW kettle? Here's a hint. You need the equation that links current and electrical power. [Music] We use P equals IV. We need the current. So, rearranging, we get current equals power divided by voltage. So, 2,00 W, that's 2 kW, divided by 230 because that's main's voltage, gives us 8.7 amp. The three types of fuse we use are generally 3, 5, and 13 amp. So, we need a 13 A fuse for this kettle. Question 12. What are step up and step down transformers and where and why are they needed in the national grid? A step up transformer increases the voltage of the electricity from a power station before it enters the grid's network of cables. This is important as it decreases the current. This reduces the amount of energy or power lost as heat due to the resistance of the cables. A step down transformer is at the other end. It reduces the voltage down to a much safer 230 volts for use in homes and businesses. Question 13. Just for triple. What kind of charges at the center here producing this electric [Music] field? Electric field lines show the direction of force on a positive charge. If it was placed in the field, that would mean it's being repelled from whatever's at the center. So, that must mean it's a positive charge at the center. Question 14. How do you find the density of regular and irregular [Music] objects? The equation for density is mass divided by volume. You get the mass by using a top pattern balance. For a regular object, that's an object for which the volume can be calculated. Say a cuboid, you measure all three sides using a ruler or a verier caliper, then multiply all three sides together to get the volume. For an irregular object, say for a chest piece, you submerge the object in a displacement or Eureka can. You collect the water, then put that into a measuring cylinder to find the volume. Question 15. What is the definition of internal energy? And why does temperature stay constant during the melting or evaporating of a [Music] substance? Internal energy is the sum of kinetic and potential energies of all particles in a substance. Temperature stays constant during a change of state because the energy supplied to the substance at these points is being used to overcome the forces of attraction between the particles. This only increases the potential energy of the particles. It's only once melted or evaporated that the kinetic energy of the particles can increase again and this is an increase in temperature. Question 16. Here's the equation for specific heat capacity. Thus, change in thermal energy or heat equals mass in kilogram time specific heat capacity time temperature change in degrees Celsius. What mass of water at 20° C initially can be raised to a temperature of 100° C with 504 kJ of heat supplied. The SHC of water is 4,200 JW per kg per degree C. [Music] Delta t is 80°. We want to calculate m. So we need to rearrange the equation to get m= delta e / c * delta t or delta theta. So 504,000 jw. Did you remember to convert kjles into jewels by multiplying by a,000 divided by 4,200 * 80? That's our temperature difference. Don't forget your brackets again. That gives us 1.5 kg. Question 17. How much energy would it take to melt 50 g of [Music] ice? We use the specific latent heat equation. E or delta E equals ML. Energy or heat equals mass in kg time the specific latent heat. So that's 0.05 kg * 334,000 JW per kg. That means we need 16,700 jewels of energy to do this. Question 18. Explain the three ways you can increase gas [Music] pressure. You can decrease the volume or add more gas. Both of these result in particles colliding more frequently with the walls of the container, say the walls of a balloon. You can also heat the gas. This increases the kinetic energy of the particles, meaning they not only move faster, so collide with the walls more frequently, but they also collide with a greater force. Question 19. Just for triple, the gas law for GCSE anyway is this. PV equals a constant for a container of gas if the temperature stays constant. Atmospheric gas pressure is 101 kilopascals. What would the new pressure be if you took some of this gas and compressed it to half the volume? the pressure would double to 202 kilopascals. This is because pressure and volume are inversely proportional. To prove it, we can write P1 V1 equals P2 V2. One just being before, two being after. Rearranging it to find P2, the pressure afterwards, and putting in the numbers, just using 1 and 0.5 for the volumes because we know it's just been halfed, we end up with 202. As this is a proportionality or ratio question, ultimately we can use the shortcut of not converting units. Our answer will just be in the same unit as what we put in kilopascals in this case. Question 20. What did Rutherford discover about the atom and [Music] how? Rutherford fired alpha particles which are positively charged at a thin gold leaf. Most went through, but some were deflected back. This shows every atom is mostly empty space but they must have a small positive charge at the center which we call the nucleus. Question 21. What are alpha, beta and gamma radiation and what are they stopped [Music] by? Alpha radiation is alpha particles which are essentially helium nuclei. That's two protons and two neutrons. They can be stopped or absorbed by a piece of paper. Beta or beta particles are high energy electrons. They're absorbed by a few millimeters of aluminium. Gamma radiation is high energy EM electromagnetic waves. They aren't stopped by anything, but they can be reduced by being absorbed by lead or concrete. Question 22. Complete these two nuclear decay equations. You'll definitely want to pause for this one. [Music] An alpha particle has a mass of four and a proton number atomic number of two. Taking that away from the uranium numbers, we're left with 230 and 90 on the thorium nucleus left over. A beta particle has a mass of basically zero. So we put that as its mass and it has an atomic number of minus1. So the mass of the daughter nucleus left over doesn't change. But be careful with the atomic number as it must go up by one. Question 23. Give three sources of background radiation. Possible sources are cosmic rays, radon gas, medical equipment, nuclear weapons, and some food like bananas. Don't get me started on radioactive bananas. Question 24. The activity of a radioactive sample decreases from 120 beckarel to 15 bearel in 24 days. What is its [Music] halflife? Remember how many half lives. So 120 to 60 is one halfife. Half again to 30 then to 15. That's three half lives. If three half lives is 24 days, one half life is 24 / 3 that's 8 days. Question 25 just for triple. Where does the energy come from in fision and fusion? During fision or fusion, the mass of the nuclear fuel decreases. This mass is turned into energy. Leave a like and a comment if you found this helpful. All the best in your exam, and I'll see you next time.