A-Level Physics Specification

OCR B H557

Section 6.1.2: Charge and field

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#6.1.2a(i)

uniform electric field \(E = \dfrac{V}{d} \)

#6.1.2a(ii)

the electric field of a charged object, and the force on a charge in an electric field; inverse square law for point charge

Spherically symmetrical charged conductor is equivalent to a point charge at its centre

#6.1.2a(iii)

electrical potential energy and electric potential due to a point charge; \(\dfrac{1}{r} \) relationship

#6.1.2a(iv)

evidence for discreteness of charge on electron

Such as the Millikan oil drop experiment

#6.1.2a(v)

the force on a moving charged particle due to a uniform magnetic field

#6.1.2a(vi)

similarities and differences between electric and gravitational fields.

#6.1.2b

Make appropriate use of:

(i) the terms: charge, electric field, electric potential, equipotential surface, electronvolt

by sketching and interpreting:

(ii) graphs showing electric potential as area under a graph of electric field versus distance, graphs showing changes in electric potential energy as area under a graph of electric force versus distance between two distance values

(iii) graphs showing force as related to the tangent of a graph of electric potential energy versus distance, graphs showing field strength as related to the tangent of a graph of electric potential versus distance

(iv) diagrams of electric fields and the corresponding equipotential surfaces.

#6.1.2c(i)

for radial components
\(F_{electric} = \dfrac{kqQ}{r^2}\),
\(E_{electric} = \dfrac{F_{electric}}{q} = \dfrac{kQ}{r^2}\) where \(k = \dfrac{1}{4πε_0} \)

#6.1.2c(ii)

\(E_{electric} = -\dfrac{dV_{electric}}{dr} \),
\(E_{electric} = \dfrac{V}{d} \) (for a uniform field)

#6.1.2c(iii)

electrical potential energy = \(\dfrac{kQq}{r} \),
\(V_{electric} = \dfrac{kQ}{r}\)

#6.1.2c(iv)

\(F = qvB \)