Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Electromotive Force
Document related concepts
no text concepts found
Transcript
Resistors in Series When resistors are connected in series there is only one path through the resistors. Since current is not used up in a resistor (the resistor dissipates energy), the current is the same in the resistors. The voltage from the EMF is split between the resistors. The resistor with the largest resistance will have the largest voltage. If one resistor is removed, there is no current in the circuit as the circuit is open. Equivalent Resistance in a Series Circuit The equivalent resistance in a series circuit is the resistance of a single resistor where the current is the same through the equivalent resistor as the resistors in the circuit. π = π1 + π2 πΌπ π = πΌπ 1 + πΌπ 2 π π = π 1 + π 2 (Conservation of energy) Equivalent Resistance in a Series Circuit For resistors connected in series, the equivalent resistance is the sum of the resistances of the resistors. π π π = π 1 + π 2 + β― + π π = π π π=1 The equivalent resistance in a series circuit is always larger than the largest resistance in the circuit. Resistors in Parallel When resistors are connected in parallel, each resistor is directly connected to the EMF. The voltage on each resistor is the same as the voltage on the EMF. The current from the EMF is split between the resistors. The resistor with the smallest resistance will have the largest current. The current in a resistor is the same as if the other resistor is not in the circuit. Removing on resistor has no effect on the other. However, the current from the EMF will decrease. Resistors connected in parallel draw more power from the EMF than resistors connected in series. Equivalent Resistance in a Parallel Circuit The equivalent resistance (Rp) in a parallel circuit is the resistance of a single resistor where the voltage is the same in the equivalent resistor as the resistors in the circuit. πΌ = πΌ1 + πΌ2 π π π = + π π π 1 π 2 1 1 1 = + π π π 1 π 2 (Conservation of Charge) Equivalent Resistance in a Parallel Circuit For resistors connected in a parallel circuit, the reciprocal equivalent resistance is the sum of the reciprocals of the resistances of the resistors. 1 1 1 1 = + + β―+ = π π π 1 π 2 π π π π=1 1 π π The equivalent resistance in a parallel circuit is always smaller than the smallest resistance in the circuit. Practice Questions Question 1 A 45V potential difference is placed across a 5β¦ resistor and a 10β¦ resistor connected in series. a. What is the equivalent resistance of the circuit? b. What is the current through the circuit? c. What is the voltage drop across each resistor? d. What is the voltage drop across the circuit? Question 2 Three resistors of 60 β¦, 30 β¦ and 20 β¦ are connected in parallel across a 90- V difference in potential. a. Find the equivalent resistance of the circuit. b. Find the current in the entire circuit. c. Find the current in each branch of the circuit. Question 3 A 30 β¦ is connected in parallel with a 20 β¦ resistor. The parallel connection is placed in series with an 8 β¦ resistor, and the entire circuit is placed across a 60 V difference of potential. a. What is the equivalent resistance of the parallel portion of the circuit? b. What is the equivalent resistance of the entire circuit? c. What is the current in the entire circuit? Practice Questions Question 3 Contd. d. What is the voltage drop across the 8 β¦ resistor? e. What is the voltage drop across the parallel portion of the circuit? f. What is the current in each line of the parallel portion of the circuit? Practice Questions Question 4 In the figure below, a. Find the equivalent resistance in the circuit. b. Find the current drawn by the battery. c. Find the current in the 10, 12 and 15 ohm resistors.
Related documents