ELM-004 · Direct current Sample material

Direct current. Ohm's laws

Electric current and its characteristics (current, current density), the resistance of a conductor and its temperature dependence, electromotive force, Ohm's law in integral and differential form, Ohm's law for a closed circuit.

Estimated time: 3 h 6 activities

Learning objective

Explain current, current density and the conditions for a current to exist.
Study how the resistance of a conductor depends on its geometry, material and temperature.
Master the concepts of electromotive force and extraneous (non-electrostatic) forces.
Learn to apply Ohm's law to a circuit section, a non-uniform section, a closed circuit and in differential form.

Expected outcomes

Can calculate the resistance of a wire from its dimensions and material, and its new resistance when the temperature changes.
Can find the equivalent resistance of resistors in series and in parallel.
Can calculate the current in a closed circuit, the terminal voltage of a source and the short-circuit current.
Can determine the emf and internal resistance of a source from two measurements.

Interactive modelOhm's law for a complete circuit

Activities

Lecture
Lecture · 1 h 20 min · required
Solving problems on direct electric current
Practice · 1 h 20 min · required
Study of Ohm's law for a circuit section
Laboratory · 1 h 20 min · optional
Determination of the emf and internal resistance of a current source
Laboratory · 1 h 20 min · optional
Sources of electric current. Rechargeable batteries
Self-study · 6 h · optional
Final test
Test · 20 min · required · pass ≥ 70%

Completion conditions

  • Lecture
  • Solving problems on direct electric current
  • Final test — at least 70%