40 Questions
What is the primary function of the Earth's magnetic field in relation to the solar wind?
To protect us from the solar wind by deflecting and concentrating the harmful particles at the poles
In what direction do magnetic field lines point?
From the north pole to the south pole
What is represented by the concentrated field lines at the poles of a bar magnet?
The strongest part of the magnetic field
What is the purpose of a toroidal container in nuclear fusion?
To generate a near uniform circular magnetic field to fuse high energy protons
What is the result of the interaction between the solar wind's magnetic field and the Earth's magnetic field?
The deflection and concentration of the harmful particles at the poles, causing the aurora borealis and the aurora australis
What is the difference between magnetic flux density and magnetic field strength?
There is no difference; they are interchangeable terms
What is an example of a near uniform magnetic field?
The field between the poles of a horseshoe magnet
What is the shape of the container used to generate a uniform magnetic field in nuclear fusion?
Toroidal (doughnut-shaped)
What is the characteristic of iron atoms in a magnetic field?
They tend to align with the field, causing their electrons to move in an ordered way.
What is the direction of the induced north pole in an iron filing in a magnetic field?
It points in the direction of the magnetic field at that point in space.
Why do the iron filings shift their positions in the presence of a permanent magnet?
To line up with the magnetic field.
What is the purpose of a soft core in an electromagnet?
To enhance the magnetic field produced by the coil.
How does the number of turns in a coil affect the magnetic field produced by an electromagnet?
A coil with more turns causes a greater magnetic field.
What is the difference between an electromagnet and a permanent magnet?
An electromagnet uses a current-carrying wire to create a magnetic field, while a permanent magnet has a permanent magnetic field.
What is the pattern of iron filings used to demonstrate?
The magnetic field around a permanent magnet.
What is the role of the current in an electromagnet?
To generate the magnetic field.
What is the direction of the force acting on a particle moving in a magnetic field, and what is the resulting trajectory of the particle?
The force acts perpendicular to the magnetic field, and the resulting trajectory of the particle is a circle.
Why is the speed of the particle unchanged as it moves in a magnetic field?
The speed of the particle is unchanged because the work done on the particle is equal to the change in kinetic energy, and no work is done.
What is the formula for centripetal acceleration, and how is it related to the force required to create this acceleration?
The formula for centripetal acceleration is 𝑎𝑎 = 𝑣𝑣 2 / 𝑟𝑟, and the force required to create this acceleration is 𝐹𝐹 = 𝑚𝑚𝑎𝑎 = 𝑚𝑚𝑣𝑣 2 / 𝑟𝑟.
What is the relationship between the radius of the circle, the speed of the particle, the mass of the particle, its charge, and the magnetic field strength?
The radius of the circle depends on the speed of the particle, the mass of the particle, its charge, and the magnetic field strength, and is given by 𝑟𝑟 = 𝑚𝑚𝑣𝑣 / 𝐵𝐵𝑞𝑞.
Why is there no work done on the particle as it moves in a circular path?
There is no work done on the particle because the force is centripetal and the particle follows a circular path, resulting in no displacement in the direction of the force.
What is the definition of work done on a particle, and how is it related to the change in kinetic energy?
Work done is defined as the product of the force and the displacement in the direction of the force, and is equal to the change in kinetic energy of the particle.
What is the nature of the acceleration experienced by a particle moving in a magnetic field?
The acceleration experienced by a particle moving in a magnetic field is centripetal.
What is the relationship between the magnetic field strength and the radius of the circle?
The magnetic field strength is inversely proportional to the radius of the circle, given by 𝑟𝑟 = 𝑚𝑚𝑣𝑣 / 𝐵𝐵𝑞𝑞.
What is the purpose of a step-down transformer in a phone charger?
To lower the voltage supplied to the phone.
What is the advantage of using an oscilloscope over a voltmeter when measuring the voltage across the input and output of a transformer?
An oscilloscope can more effectively measure the changing voltage.
What is the purpose of a variable resistor (rheostat) in an experiment to investigate the efficiency of a transformer?
To vary the current at a constant voltage.
How is the efficiency of a transformer estimated?
By calculating the ratio of output power to input power.
What is the advantage of using laminated iron in the core of a transformer?
It reduces power loss to magnetic heating by reducing eddy currents.
Why are soft iron cores more efficient in transformers?
They are easier to magnetize and demagnetize, and are more susceptible to changing magnetic fields.
What is the purpose of using lower resistance wires in the coils of a transformer?
To reduce power loss to resistive heating.
What is the formula to calculate the efficiency of a transformer?
η = (IpVp / IsVs) × 100%.
What happens to the iron atoms in the iron core due to a changing magnetic field?
The iron atoms constantly align with the field
What is the purpose of using step-up transformers in the transmission of electrical energy across the national grid?
To reduce power losses
Why is the resistance of transmission lines often high despite being made of low resistivity metal and having a large cross-sectional area?
Because of the large distances between power stations and consumers
What is the equation that relates power loss to current and resistance?
𝑃𝑃𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 = 𝐼𝐼 2 𝑅𝑅
What is the purpose of step-down transformers in the transmission of electrical energy?
To decrease the voltage from the transmission cables
Why do mobile phones require a lower voltage than the 230V mains supply?
Because some components may be sensitive to high voltages and technical faults may occur
What is an example of a device that uses transformers in many homes?
A mobile phone charger
What is the main application of transformers in the transmission of electrical energy?
To reduce power losses in transmission lines
Understand the interaction between a permanent magnet and iron filings, including the alignment of atoms and the creation of induced magnetic fields. Learn how the magnetic fields of the permanent magnet and the iron filings interact with each other. Test your knowledge of magnetism and its effects on ferromagnetic materials.
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