# Resistance of a cell

This allows us to plot V as y against I as x, in order to find the values of E and -r. Because the equation is now in the format y = mx + c, we know that E will be the y-intercept value, and -r will be the gradient. I plotted three sets of data for current and voltage: my original results, the values including uncertainties that would give the largest values of E and -r, and the values including uncertainties that would give the smallest values of E and -r.From the graph, I can calculate both the EMF and the internal resistance of the battery.

The y-intercept gives me the value of E, because according to the equation V = (-r) I + E, when the x-value of current (I) is zero, the equation will be simplified to V = E. The gradient of the line of best fit gives me the negative value of internal resistance (r), because the gradient can be calculated by y/ x, which is represented as V/ I in our results. From my results, I found that voltage and current had a negative correlation, as as one increases, the other decreases.The values I obtained are EMF = 2.402V and r = 3.814?. The literature value for EMF was 2.

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35V, because when I was recording results, I obtained this value for voltage when current equaled zero. The literature value and the experimental value have a relatively small difference, which indicates that the experiment could be considered successful to some extent. Evaluation The investigation showed no anomalous results in general, as increasing values of voltage all resulted in decreasing values of current. This is consistent with previous knowledge learned.The same pieces of equipment were used throughout the entire experiment, as changing these would have affected the results from the battery. There were limitations as to the accuracy of the readings that I could obtain using said equipment; to reduce the possible error range of the final result, I could replace the current pieces of equipment with more accurate ones. The variable resistor was not given time to cool down in between our recordings, so the temperature might’ve affected the results in some way.

I only obtained five results, which might not have been enough for the experiment to really be considered accurate. Next time, I will record more paired values of the current and the voltage, as well as repeat the experiment at least once to reduce the chance of inaccuracy. Purpose: Find the efficiency of three different spheresVariables: Manipulated Variable: the type of ball used Responding Variable: height of the first bounce of the ball when it is dropped from 2m Controlled Variables: the force applied on the ball, the height at which the ball is dropped, flat surface Hypothesis: the efficiency of a sphere is going to depend largely on its mass and size, the less the mass and size, the higher that it will bounce, because the lesser the mass, the lesser amount of energy will be needed to push it up against the downward pull of gravity, and the smaller the size, the lesser friction air will create when it is bouncing up. This means that the golf ball is possibly going to be the one that bounces the highest and the most efficient, the tennis ball will bounce the second highest and the second most efficient, and the field hockey ball will bounce the third highest and the least efficient.