# P451

To determine the effects of voltage and resistance on the current, a physicist designs a circuit with variable resistance and voltage. The circuit contains two switches, one that can be opened to one of the two possible voltage sources, and one that can be opened to one of the two possible resistors. Two locations are marked on Figure 1 (points A and B) where an ammeter may be attached to read the current. The physicist takes readings at both point A and point B for the four possible combinations of resistance and voltage. The circuit is shown below in Figure 1.

**Figure 1**. Circuit schematic.

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