20: Electric Current, Resistance, and Ohm's Law

What is electric current? Symbol, unit

I

In Amperes (A)

1 A = 1 C/s

How are I, delta Q, and delta t related?

I = delta Q/delta t

Where I is electric current, Q is charge, and t is time

How are I, n, q, A, and v_d related?

I = nqAv_d

Where I is current, A is cross sectional area of a wire, n is the free charge density of the wire, q is charge of each carrier, and v_d is drift velocity

How are I, V, and R related?

V = IR

Where V is voltage, I is current, and R is resistance

What is resistance? Symbol, unit

Omega

Ohms

1 Ohm = 1 V/A

How are R, rho, L, and A related?

R = (rho)L/A

Where R is resistance, L is length, A is cross sectional area, and rho is the resistivity of the material

How are temperature and resistivity related?

rho = (rho₀) (1 + (alpha)(delta T))

Where rho is resistivity, alpha is temperature coefficient of resistivity, and T is temperature

How is resistance related to temperature?

R = R₀ (1 + (alpha)(delta T))

Where R is resistance, alpha is temperature coefficient of resistivity, and T is temperature

How are P, I, V, and R related?

P = IV = V²/R = I²R

Where P is power, I is current, V is voltage, and R is resistance

How are E, P, and t related?

E = Pt

Where E is energy, P is power, and t is time