Experiment 11: Electrical meters or \"like amber from Mesctpov, elektron, the Gr

Question

Experiment 11: Electrical meters or "like amber from Mesctpov, elektron, the Greek word for like means "of amber" city Lui twitched when struck by an e : Alesieu when struck by zos In 1780, he discovered thuat the muscles of dead frogst legs ta(1745- 1827) inventor of the electrical battery in : André-Marie Hans Christian Orsted (1777-1851) Georg suche S1 ) discovered that electric currents create magnetic fields, which was the first aric Ampère (1775 1836) French physicist the restuionality betw854) He found that (in most cases) there is a direct proportionality between the difference the resultant electric current. connection found between electricity and magnetism e potential difference (voltage) applied across a conductor and Purpose (1) To use a galvanometer asilmcivoleter (2) To convert a galvanometer into a reading (3) To determine the characteristics of a galva neter (b) a resistance decade box, (e) a rheostat (for part 2) (d) batteries Theory a) basics A galvanometer is an instrument used to detect and measure s main working part is a tiny coil suspended between the cmanent magnct The coil will experience a torque when a attached to a pointer and the current in the wire of the coil. current passes through the wire of the coil. The coil is a spring so that the amount of deflection of the pointer is proportional to The maximum deflection of the galvanomcter needle is limited by the current which the galvanometer resistance can support. Too much current will damage the galvanometer. Note that the galvanometer (as any other current carrying element of an electrical circuit) has internal resistance, which we shall indicate as RG b) a galvanometer as a milliammeter To measure a current the meter has to be placed in series in the circuit so that the current flows through it. As mentioned above, the total resistance of the circuit has to be such that the current does not exceed the maximum current the galvanometer can support To be a reliable meter, the internal resistance Rg of the meter has to be low, so that it does not significantly alter the current flow in the circuit itself

Explanation / Answer

Part1:

b. Why is R*I is almost constant? : R is resistance and I is current. For given value of resistance, current will flow according to it. If R is large then I will be small, and it obeys the ohm's law which tells R*I=V, where V is voltage applied to circuit, As, One parameter increses another decreses then the product turns out to be constant.

c. Slope will be simply: y/x i.e R/(1/I) =R*I it gives again a constant = RI = porduct of R and I which should be equal to your data.

And intercept on y-axis gives the internal resistance of circuit.

PART 2:

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