# ocr-combined-science-a-papers

## OCR Combined Science A – P6/P12

#### Wave Speed

Wave speed is given in meters per second (the number of waves that pass per second). Wavelength is measured in meters and frequency is measured in hertz (Hz), or number of waves per second. Demo In this tutorial you will learn how to calculate the speed of a wave. The equation for this calculation is written like this: $v = { \text f \; \text x \; \lambda }$ Chilled practice question Calculate the velocity of a wave with a wavelength of 6 m and a frequency of 50 Hz Frozen practice question Find the velocity of a wave which has a time…

#### Efficiency

The efficiency of a device is the proportion of input energy that is converted to useful energy. What is Efficiency? The efficiency of a device is the proportion of input energy that is converted to useful energy. Efficiency is a measure of how much work or energy is conserved in an energy transfer, work or energy can be lost, for example as wasted heat energy. The efficiency is the useful energy output, divided by the total energy input, and can be given as a decimal always less than 1 or a percentage. No machine is 100% efficient. Efficiency equation To calculate Efficiency we use this…

#### Transformers

A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to “step up” or “step down” voltages and is based on the magnetic induction principle. Demo In this tutorial you will learn how to calculate voltages in step up and step down transformers. The equation is written like this: ${ \text V_{1} \; \text / \; \text V_{2} \; \text = \; \text N_{1} \; \text / \; \text N_{2} \;}$ Chilled practice question A transformer has 300 turns on its primary coil and 100 turns on it secondary coil. What…

#### The Motor Effect

A current-carrying wire or coil can exert a force on a permanent magnet. The force increases if the strength of the magnetic field and/or current increases. This is called the motor effect. Demo In this tutorial you will learn how to calculate the force on a wire carrying a current in a magnetic field. The equation is written like this: $F = { \text B \; \text x \; \text I \; \text x \; \text L}$ Chilled practice question Calculate the force on a wire carrying a current of 3 A. 0.25 m of the wire is in the magnetic field. The magnetic flux density…

## OCR Combined Science A – P5/P11

#### Wave Speed

Wave speed is given in meters per second (the number of waves that pass per second). Wavelength is measured in meters and frequency is measured in hertz (Hz), or number of waves per second. Demo In this tutorial you will learn how to calculate the speed of a wave. The equation for this calculation is written like this: $v = { \text f \; \text x \; \lambda }$ Chilled practice question Calculate the velocity of a wave with a wavelength of 6 m and a frequency of 50 Hz Frozen practice question Find the velocity of a wave which has a time…

#### Force on a Spring

When a force acts on a spring it is stretched or compressed, its length will changes by an amount e from its original length. Demo In this tutorial you will learn how to calculate the force on a spring given its extension and spring constant. Note-Some mobile devices may require you to tap full screen during playback to view video content. The equation for this calculation is written like this: $F = { \text k \; \text x \; \text e}$ Chilled practice question Copy out the question and attempt to calculate the answer before watching the solution. Write down the equation…

#### Force, Mass and Acceleration

An object of constant mass accelerates in proportion to the force applied. Demo In this tutorial you will learn how to calculate the force applied to an object if you are given its mass and acceleration. The equation for this calculation is written like this: $F = { \text m\; \text x \; \text a}$ Chilled practice question Calculate the force applied to cannon ball which accelerates at 7m/s2 which has a mass of 5 Kg. Frozen practice question A rocket has a driving force of 15 N and a mass of 250 g. Calculate the acceleration of the rocket. Science in context Force (N)…

#### Kinetic Energy

In physics, the kinetic energy (KE) of an object is the energy that it has due to its motion. It is defined as the work needed for an object of a known mass to accelerate to a given velocity. What is Kinetic energy? In physics, the kinetic energy (KE) of an object is the energy that it has due to its motion. It is defined as the work needed for an object of a known mass to accelerate to a given velocity. Kinetic energy equation To calculate Kinetic energy we write the equation like this. $E_k = { 1 \over2} mv {^2}$ Kinetic energy demo In this tutorial you will learn how…

#### Specific Heat Capacity

Specific heat capacity is how much heat energy is required to raise 1 kg of a substance by 1 °C. What is Specific heat capacity? Specific heat capacity is how much heat energy is required to raise 1 kg of a substance by 1 °C. Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property and different materials have a different specific heat capacities. Specific heat capacity equation To calculate Specific heat capacity we write the equation like…

#### Power

The quantity power is the rate at which work is done. The quicker work is done the greater the power. What is Power? The quantity power is the rate at which work is done. The quicker work is done the greater the power. The standard metric unit of power is the Watt. The calculation of power is the work done in Joules divided by a unit of time seconds. 1 Watt is equivalent to 1 joule of work done per second. Many machines have their power rating displayed upon them in Watts, the higher the value the greater the power…

#### Elastic Potential Energy

Stretching or squashing an object can transfer energy into its elastic potential energy store. What is Elastic potential energy? Stretching or squashing an object can transfer energy into its elastic potential energy store. Elastic energy is the mechanical potential energy stored in the material. Elastic energy occurs when objects are compressed, stretched or deformed. Elastic potential energy equation To calculate Elastic potential energy we use this equation. $E_e = { 1 \over2} ke {^2}$ Elastic potential energy demo In this tutorial you will learn how to calculate the energy stored in a stretched spring. Chilled practice question A spring is…

#### Charge

The size of the current is the rate of flow of charge. Electrons are negatively charged particles which transfer energy through wires as electricity. What is Charge? The size of the current is the rate of flow of charge. Electrons are negatively charged particles which transfer energy through wires as electricity. Charge is measured in coulombs (C). Electrons are really small and the effect of one electron would be really difficult to measure, It is easier to measure the effect of a large number of electrons. One Coulomb of charge contains 6 × 1018 electrons. Charge equation To calculate Charge we use this…

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