Physics Concepts: Refraction & Energy Transfer

Questions and Answers

Define refraction.

Change in speed of light.

Why is acceleration not constant even though the engine produces a constant force? (List three reasons)

Air resistance. 2. Increases as speed increases. 3. Reducing resultant force.

Why does the telescope orbit Earth fastest when it is closest to Earth? (List three reasons)

GPE decreases. 2. KE increases. 3. Total energy conserved.

How does a microwave transfer energy to heat up all of the potato? (List four steps)

<ol> <li>Microwaves are EM waves. 2. Penetrates into the food. 3. Causes water molecules in food to vibrate. 4. Conduction through the rest of the potato.</li> </ol> Signup and view all the answers

Use ideas about particles to explain why evaporation leads to cooling. (List four points)

<ol> <li>Sweat will be evaporated as liquid. 2. Molecules with higher KE will evaporate. 3. Lower energy particles remain. 4. Reducing temperature.</li> </ol> Signup and view all the answers

Suggest why a runner might cool down too quickly if he does not wear a foil sheet. (List two reasons)

<ol> <li>Still covered in sweat. 2. Not generating as much heat as before.</li> </ol> Signup and view all the answers

Use ideas about particles to explain why the cooled balloon is smaller. (List four points)

<ol> <li>Less KE. 2. Less frequent collisions with the walls of the balloon. 3. On average. 4. Reducing the amount of force exerted on the balloon.</li> </ol> Signup and view all the answers

How to ensure results were reliable? (List two methods)

<ol> <li>Repeat and take average. 2. Exclude anomalies.</li> </ol> Signup and view all the answers

What is meant by the term magnetic field line?

Lines that show the direction of the magnetic field. Signup and view all the answers

Explain why the washing machine is fitted with a fuse. (List two reasons)

<ol> <li>Acts as a safety device/reduces danger. 2. In case of fault.</li> </ol> Signup and view all the answers

Explain why alpha particles and beta particles have different penetrating powers. (List five points)

<ol> <li>Alpha particles have less penetrating power. 2. Alphas have more charge. 3. Alphas cause more ionization. 4. Alphas mass/size is bigger. 5. Kinetic energy of alpha particles is quickly lost by ionization.</li> </ol> Signup and view all the answers

The image in a plane mirror is a virtual image. How to tell from the diagram?

The virtual image is drawn in dotted lines. Signup and view all the answers

Suggest two advantages of sending signals using optical fibres.

<ol> <li>Less prone to noises. 2. Sends more information per second.</li> </ol> Signup and view all the answers

Describe the method the students should use for this investigation. (List seven steps)

<ol> <li>Connect the circuit. 2. Read ammeter. 3. Read voltmeter. 4. Measure length with ruler. 5. Take readings for different lengths/vary the length of wire. 6. Repeat the readings. 7. Disconnect between each reading.</li> </ol> Signup and view all the answers

Why does the comet travel fastest at this point in the orbit?

<ol> <li>Closest to the sun. 2. Gravitational force greatest.</li> </ol> Signup and view all the answers

Explain how nuclear fission shown in the diagram can lead to a chain reaction. (List three points)

<ol> <li>Nucleus splits. 2. Releasing neutrons. 3. Which will hit with another nuclei.</li> </ol> Signup and view all the answers

Nuclear fission releases energy. Explain the form that this energy takes.

<ol> <li>Released as kinetic energy. 2. Of the products formed/neutrons/daughter nuclei.</li> </ol> Signup and view all the answers

What is the purpose of a moderator?

Slow down neutrons. Signup and view all the answers

Suggest a property of radio waves that makes them suitable for use in communication.

<ol> <li>Travels at the speed of light. 2. Can transfer information.</li> </ol> Signup and view all the answers

Explain why the feather reaches the ground after the hammer.

<ol> <li>Feather is lighter. 2. Reaches terminal velocity quicker than hammer.</li> </ol> Signup and view all the answers

Explain why wind turbines have not replaced power stations.

<ol> <li>Spoils the view. 2. Large site needed.</li> </ol> Signup and view all the answers

Describe the process of convection that causes air movement. (List seven steps)

<ol> <li>Air is warmed. 2. Hot air expands. 3. Hot air becomes less dense. 4. Hot air rises. 5. Cool air becomes more dense. 6. Cool air falls. 7. Process repeated.</li> </ol> Signup and view all the answers

Study Notes

Refraction

Refraction is the change in speed of light as it passes through different media.

Acceleration and Forces

Acceleration is not constant despite a constant engine force due to:
- Air resistance affecting motion.
- Increased air resistance with higher speed.
- Resulting reduction in net force acting on the object.

Telescope Orbit Dynamics

A telescope orbits Earth faster when closest due to:
- Decrease in gravitational potential energy (GPE).
- Increase in kinetic energy (KE).
- Conservation of total energy through the orbit.

Microwave Energy Transfer

Microwaves heat food by:
- Being electromagnetic waves that penetrate food.
- Causing water molecules in the food to vibrate.
- Transferring heat through conduction within the food.

Evaporation and Cooling

Evaporation cools surfaces because:
- Sweat evaporates as a liquid.
- High kinetic energy (KE) molecules escape first.
- Remaining molecules with lower energy lead to reduced temperature.

Runner Cooling Too Quickly

A runner not wearing a foil sheet may cool rapidly due to:
- Sweat remaining on the skin surface.
- The body generating less heat post-activity.

Cooling Balloon Explanation

A cooled balloon becomes smaller because:
- Particles have less kinetic energy.
- Decreased frequency of collisions with balloon walls.
- Results in lower force exerted internally and reduced rubber tension.

Ensuring Reliable Results

Reliability in experiments can be improved by:
- Repeating the experiment and calculating an average.
- Excluding any anomalous data.

Magnetic Field Lines

Magnetic field lines represent the direction and strength of the magnetic field.

Washing Machine Fuse

A fuse in a washing machine serves to:
- Act as a safety device to reduce hazards.
- Disconnect in case of a fault or excessive current, preventing fire.

Alpha and Beta Particle Penetration

Differences in penetrating power between alpha and beta particles arise from:
- Alpha particles being less penetrating due to higher charge, greater mass, and rapid ionization.
- Alpha particles losing kinetic energy quickly due to collisions with atoms.

Virtual Image in Plane Mirror

A plane mirror creates a virtual image, which is indicated by:
- The image shown with dotted lines on diagrams.

Advantages of Optical Fibers

Benefits of using optical fibers for communication include:
- Reduced susceptibility to noise and heating.
- Higher data transmission rates.

Investigation Methodology

To conduct a conductivity investigation:
- Connect the circuit and read the ammeter and voltmeter.
- Measure wire lengths using a ruler and vary the lengths.
- Repeat measurements, ensuring to disconnect the circuit between readings to prevent wire heating.

Comet Speed at Closest Point

A comet travels fastest at its closest point to the sun due to:
- The highest gravitational force exerted at this proximity.

Nuclear Fission and Chain Reaction

In nuclear fission:
- The nucleus splits and releases neutrons.
- These neutrons can initiate further fission in neighboring nuclei.

Energy Release in Nuclear Fission

The energy released from nuclear fission is primarily in the form of:
- Kinetic energy of the resulting particles (neutrons or daughter nuclei).

Moderator Purpose in Nuclear Reactions

A moderator's role is to slow down neutrons during fission reactions.

Properties of Radio Waves

Properties that make radio waves effective for communication:
- Travel at the speed of light, enabling rapid signal transfer.
- Capable of traveling long distances and can diffract around obstacles.

Feather and Hammer Experiment

In an experiment with a feather and hammer:
- The feather, being lighter, reaches terminal velocity faster.
- The smaller inertia of the feather results in a lower impact velocity upon hitting the ground.

Wind Turbines Challenges

Wind turbines have limitations compared to power stations due to:
- Visual pollution and disruption to natural habitats.
- Requirement for large, windy sites, with individual turbines producing less energy.
- High initial construction and ongoing maintenance costs.

Air Movement through Convection

Air movement caused by convection entails:
- Warm air expansion, resulting in decreased density.
- Hot air rising while cool air sinks, leading to continuous air circulation.

Storm Cloud Discharge

Upon discharge, a storm cloud releases:
- An electric charge resulting in lightning.
- Rapid equalization of charged areas to restore balance, which can also cause thunder.

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Description

This quiz covers fundamental physics concepts including refraction of light, acceleration influenced by forces, telescope dynamics in orbit, microwave energy transfer, and the cooling effect of evaporation. Test your understanding of these physical principles and their applications.