Figure 8, shows a shows a graph of potential difference V (volts) against a current I (amperes) for a certain device.

      

Figure 8, shows a shows a graph of potential difference V (volts) against a current I (amperes) for a certain device.
physics5232017344.jpg
From the graph:
(i) State with a reason whether or not the device obeys ohms law.
(ii) Determine the resistance of the device at;
(I) I = 1.5 A
(II) I = 3.5 A

  

Answers


John
(i) Does not obey ohm's law. current is not directly proportional to voltage.

(ii) (I) at I = 1.5 A, R = gradient of tangent at I = $\frac{9.2 - 4.8}{3.6 - 0.1}$ = 1.26 ohms

(II) at I = 3.5 A, R = gradient of tangent at I = $\frac{9.4- 7.2}{5.4 - 1.5}$ = 0.56 ohms
johnmulu answered the question on May 23, 2017 at 13:03


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