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A-Level Electric current and carrier drift, voltage and electrical power, plus d.c. and a.c. supplies

What the A-Level syllabus expects for Electric current and carrier drift, voltage and electrical power, plus d.c. and a.c. supplies, and how to practise it.

What the syllabus expects

• Understand current as how fast charge flows and solve problems with I = Q/t
• Obtain and apply I = nAvq for a conductor carrying current
  Scope: n is the carrier number density and v the drift velocity
• Apply V = W/Q, which defines voltage as the electrical work done per unit charge, in problems
• Solve problems with the power relations P = VI, P = I2R and P = V2/R
• Tell e.m.f. from p.d. by reasoning about energy
• Grasp and apply, for an alternating current or voltage, this quartet: peak value, root-mean-square (r.m.s.) value, frequency and period
• Write a sinusoidal a.c. current or voltage as x = x0 sin ωt
• Show that for a sinusoidal a.c. the mean power in a resistive load comes to half the peak power
• Separate r.m.s. from peak values, and apply Irms = I0/√2 and Vrms = V0/√2 for sinusoids
• Describe how a single diode achieves half-wave rectification of an alternating current

How it's examined

About 4% of the past-paper style questions in Rae's bank for this subject sit in this topic.

More A-Level H2 Physics topics

Physical quantities, units, measurement uncertainty and vector basics · Types of force, turning effects and conditions for equilibrium · Kinematics, uniformly accelerated motion, momentum and Newton's laws · Energy stores and transfers, work, kinetic and potential energy, fields, power and efficiency · Falling freely, the gravitational potential energy of a uniform field, and how air resistance changes the motion · Impulse and the conservation of momentum and energy · all of A-Level H2 Physics