CBSE Class 12-science Answered
IS IT TRUE THAT TO GET THE MAXIMUM CURRENT IN SERIES COMBINATION THE LOAD RESISTANCE MUST BE GRATER
THAN THE INTERNAL RESISTANCES OF IDENTICAL CELLS CONNECTED IN SERIES?IF YES WHAT IS THE REASON FOR THAT?WHAT HAPPENS IF THE CELLS WERE NON IDENTICAL?
Asked by vishnuraj | 24 May, 2012, 08:02: AM
Expert Answer
Emf and Internal Resistance
Now, real batteries are constructed from materials which possess non-zero resistivities. It follows that real batteries are not just pure voltage sources. They also possessinternal resistances. Incidentally, a pure voltage source is usually referred to as an emf (which stands for electromotive force). Of course, emf is measured in units of volts. A battery can be modeled as an emf connected in series with a resistor , which represents its internal resistance. Suppose that such a battery is used to drive a current through an external load resistor , as shown in Fig. 1. Note that in circuit diagrams an emf is represented as two closely spaced parallel lines of unequal length. The electric potential of the longer line is greater than that of the shorter one by volts. A resistor is represented as a zig-zag line.
Consider the battery in the figure. The voltage of the battery is defined as the difference in electric potential between its positive and negative terminals: i.e., the points and , respectively. As we move from to , the electric potential increases by volts as we cross the emf, but then decreases by volts as we cross the internal resistor. The voltage drop across the resistor follows from Ohm's law, which implies that the drop in voltage across a resistor , carrying a current , is in the direction in which the current flows. Thus, the voltage of the battery is related to its emf and internal resistance via
So current will be maximum when external (or load) resistance will be very much higher than internal resistance.
|
Answered by | 24 May, 2012, 10:58: AM
Concept Videos
CBSE 12-science - Physics
Asked by mailtoanjalip2005 | 16 Mar, 2024, 08:22: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by patelnamra608 | 26 Jan, 2024, 11:01: AM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by smitdholakiya28 | 17 Dec, 2023, 09:37: AM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by shivashikhar69 | 09 Dec, 2023, 02:27: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by nikhilsai2616 | 19 Nov, 2023, 01:05: AM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by snehashiragannavar773 | 21 Oct, 2023, 02:38: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by dr.strange45678 | 02 Aug, 2023, 12:31: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by komalbrar0987 | 17 May, 2023, 06:15: PM
ANSWERED BY EXPERT
CBSE 12-science - Physics
Asked by amanpanday6384 | 22 Dec, 2022, 12:42: PM
ANSWERED BY EXPERT