Electric circuits - grade 11
6 likes6,473 views
The document discusses key concepts in electric circuits including Ohm's Law, which states that current is directly proportional to voltage and inversely proportional to resistance. It explains that conductors that obey Ohm's Law are called ohmic conductors. It also covers series and parallel circuits, explaining that current is the same in all components of a series circuit while voltage splits, and that voltage is the same across parallel circuits while current splits. Finally, it defines electrical power as the rate energy is converted in a circuit and provides formulas for calculating power using voltage, current, and resistance.
Electric circuits - grade 11
- 1. 1 Everything Science www.everythingscience.co.za 11. Electric circuits Physics Grade 11
- 2. 2 Everything Science www.everythingscience.co.za Ohm's Law Ohm’s Law states that the amount of current through a conductor, at constant temperature, is proportional to the voltage across the resistor. Mathematically we write where I is the current through the conductor, V is the voltage across the conductor and R is the resistance of the conductor. I= V R
- 3. 3 Everything Science www.everythingscience.co.za Ohm's Law and conductors Conductors that obey Ohm’s Law are called ohmic conductors; those that do not are called non-ohmic conductors.
- 4. 4 Everything Science www.everythingscience.co.za Series and parallel circuits The equivalent resistance of resistors in parallel (Rp ) can be calculated as follows: The equivalent resistance of resistors in series (Rs ) can be calculated as follows: Rs=R1+R2+R3+... 1 Rp = 1 R1 + 1 R2 + 1 R3 +...
- 5. 5 Everything Science www.everythingscience.co.za More on series and parallel circuits IT=I1=I2=I3 VT =V 1+V2+V3 In a series circuit the amount of current is the same through any component in the circuit. And the total voltage of the circuit has to be equal to the sum of the voltages over all three resistors. This can be expressed as (assuming three resistors): In a parallel circuit the voltage is equal across all components in the circuit. And all the currents through each resistor must add up to the total current in the circuit. This can be expressed as (assuming three resistors): VT =V 1=V 2=V 3 IT =I1+I2+I3
- 6. 6 Everything Science www.everythingscience.co.za Electrical power and energy Electrical power is the rate at which electrical energy is converted in an electric circuit. Power (P) is measured in watts (W). Using Ohm's Law we can find two alternate forms of this expression to calculate power: The electrical energy dissipated is and is measured in joules (J). P=I⋅V P=I2 ⋅R P= V 2 R E=P⋅t
- 7. 7 Everything Science www.everythingscience.co.za For more practice see: www.everythingscience.co.za Shortcode: ESBQH