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New YorkPhysics

Electricity and Magnetism

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What is electric current, and how do voltage, current and resistance relate in a conductor?

Define current as rate of flow of charge, $I = q/t$ , state Ohm's law $R = V/I$ , and apply the electrical power equations to calculate power and energy in a resistor.
A Regents Physics answer on current, Ohm's law and electrical power: current as rate of charge flow, the voltage-current-resistance relationship, and the power and energy equations from the Reference Tables, with worked examples.
11 min answer →

How do we describe the influence of a charge on the space around it, and what is electric potential difference?

Define the electric field as force per unit charge, $E = F_e/q$ , describe the uniform field between parallel plates with $E = V/d$ , and define electric potential difference as work per unit charge, $V = W/q$ .
A Regents Physics answer on electric fields and potential difference: the field as force per unit charge, the uniform field between parallel plates, field-line diagrams, and potential difference as work per unit charge, using the Reference-Table equations, with worked examples.
11 min answer →

How does a changing magnetic field produce an electric current, and how is this used in generators?

Describe electromagnetic induction as the production of an electromotive force by a changing magnetic field through a conductor, and explain how generators and transformers use induction.
A Regents Physics answer on electromagnetic induction: how a changing magnetic field through a conductor induces an electromotive force and current, the factors that increase the induced EMF, and how generators and transformers work, with worked reasoning examples.
11 min answer →

How are magnetism and electric current related, and what force acts on a moving charge in a magnetic field?

Describe magnetic fields and the field produced by an electric current, apply $F_B = qvB$ to the force on a moving charge in a magnetic field, and explain the force on a current-carrying wire that underlies the electric motor.
A Regents Physics answer on magnetism and the motor effect: magnetic fields and field lines, the magnetic field of a current, the force on a moving charge using the Reference-Table equation, and the force on a current-carrying wire that drives electric motors, with worked examples.
11 min answer →

How do current, voltage and resistance behave differently in series and parallel circuits?

Apply the rules for series and parallel circuits to current, voltage and total resistance, and analyze simple circuits to find the current through and voltage across each component.
A Regents Physics answer on series and parallel circuits: the rules for current, voltage and total resistance in each, how total resistance increases in series and decreases in parallel, and how to analyze a simple circuit, with worked examples.
12 min answer →

How do objects become charged, and how does the force between charges depend on charge and distance?

Describe charging by friction, conduction and induction, state that charge is conserved and quantised in multiples of the elementary charge, and apply Coulomb's law $F_e = kq_1q_2/r^2$ to calculate the force between point charges.
A Regents Physics answer on static electricity and Coulomb's law: how objects are charged by friction, conduction and induction, the conservation and quantisation of charge, and how to apply the Reference-Table equation for the force between point charges, with worked examples.
12 min answer →