The force felt in a force field is a non-contact force. True or False?
True.
Is force a vector or scalar quantity?
A vector.
What are some similarities between electrostatic and gravitational forces?
● Inverse square force laws ● Potential concept ● Equipotential surfaces ● Use of field lines
What are some differences between electrostatic and gravitational forces?
The gravitational forces from masses always attract, whilst charges may repel or attract.
What is gravity?
Gravity is the universal attractive force which acts between all matter.
What is G?
The universal gravitational constant. Approx. 6.67x10¯¹¹ m³kg¯¹s¯²
What can field lines tell you about a field?
The direction of the field and the strength of the field depending on the density of the field lines.
What is 𝘨?
𝘨 is the force per unit mass in a uniform field. In a radial field, the magnitude of 𝘨 is the proportionality constant at that point between force and mass. Iet 𝘨 = GM/r²
What is gravitational potential?
The potential energy per kilogram, at any point in the field. 0 potential is defined at infinity, hence at a point close to a mass the potential of an object would be negative.
What is the work done by moving a mass in a field?
Mass x change in potential
What is the gravitational potential difference?
Gravitational potential difference is the difference in the gravitational potentials of two points in a gravitational field.
What is an equipotential surface?
A surface in which every point on the surface has the same potential.
How much work is done when you move 1km in any direction on an equipotential surface?
No work is done when moving across equipotentials, as the potential at each point is the same.
Why is gravitational potential a negative value?
Work needs to be done to move an object from inside the field to outside the field. Since outside the field’s potential is defined as 0 then the potential inside the field must be negative.
How is the orbital period related to the radius of a circular orbit?
T² ∝ R³
What equations could one use to find the speed of an orbiting satellite?
The orbiting object (mass m) is in circular motion, so we would use F = ma with F = GMm / r² rearranged to a = v² / r = ω²r. This can be solved to find speed (v), angular speed (ω), the radius of the orbit or using T = 2π / ω its period.
Compare the PE and KE of a lower orbit to a higher one.
A lower orbit (smaller r) has less potential energy and more kinetic energy than a higher orbit (bigger r).
What is the period of a geosynchronous orbit?
Geosynchronous orbits have a period of one day.
What symbol represents the permittivity of free space?
𝜀₀
When calculating the force between two particles, what can air be treated as?
A vacuum.
For a charged sphere the charge can be assumed to be at what part of the sphere?
The centre.
Which is stronger? The gravitational force of subatomic particles or the electrostatic force?
The electrostatic force.
Electric field lines always go from _____ to _____.
Electric field lines always go from positive charge to negative charge.
What is electric field strength?
The force per unit charge acting at a point in an electric field.
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Measurements and Their Errors37
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Particles42
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Electromagnetic Radiation and Quantum Phenomena13
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Progressive and Stationary Waves18
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Refraction, Diffraction & Interference38
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Mechanics36
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Materials21
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Current Electricity32
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Periodic Motion25
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Thermal21
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Gravitational Fields27
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Electric Fields9
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Capacitance16
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Magnetic Fields25
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Nuclear48
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Stationary Waves on a String21
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Interference Effects19
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Determination of g16
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Determination Of Young’s Modulus21
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Determination Of Resistivity of a Wire14
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Internal Resistance and emf12
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Simple Harmonic Motion15
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Boyle's and Charles's Laws16
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Charging and Discharging Capacitors10
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Magnetic Force on a Wire14
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Magnetic Flux Linkage12
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Inverse Square Law for Gamma Radiation16
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Magnetic Fields Mock8
