Question

1.         Measure ands record the e.m.f E of the given cell. emf=5.65V

2.         Connect an external resistance R = 1 W and measure the terminal voltage V across the resistor. 1 ohm V=4.45V

3.         Repeat step 2 using six different values of R each time measuring V. Tabulate the values of V and R.                                                                              

1 ohm	4.45 V
2 ohm	4.64
3 ohm	4.77 V
4 ohm	4.88V
5 ohm	4.96V
10 ohm	5.16V
20 ohm	5.32 V

4.         If I is the current in the external resistor R and r is the internal resistance of the cell, the equation for the whole circuit is:

            E = I(R + r)          …….(i)

            For the same current in the external resistor R, the terminal voltage is given by:

            V = IR                  …….(ii)                                                                

                                                                                               

5.         Use equations (i) and (ii) to solve for r by eliminating I and write this equation the form:   y = mx + b

Identify the independent variable and the dependent variable.          

6.         Draw an appropriate graph and measure its slope.   

7.         Use the slope of the graph to obtain a value of the internal resistance r of the cell.

I NEED HELP ON 5,6,7 PLSS!! ALSO FOR MY GRAPH WILL IT BE VOLTAGE AGAINST RESISTANCE WITH THE SLOPE change in V/ change in R?

Answer 1

(5) R E= I (Rtd) (1) ~= IR I=v R put this value of I in (1) we get E= V CR+8) ER= VR trg R[E-VJ= vo > R=1 this is of the form y=mxtab 8 rov with y=R, m=8 we have E= 5,650 y v and b=0 EV V V/EN 4.45 3.708 2 4.69 4,77 4,88 4,96 4.594 5,42 6.337 3 5 5,16 5,32 7.188 10,53 16.12 how > on plotting graph of Rus we get slope ms 1.53 since mar Ir = 1.532

III 5 -5 0 5 10 -5 « + X Yi ~ mxy + c STATISTICS RESIDUALS e plot p2 = 0.9919 p=0.9959 PARAMETERS m = 1.53535 C=-5.393