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Will the bulb glow in this circuit? Why not? I think the bulb should glow because there's a potential difference.Circuit

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The bulb will not glow. There is a potential difference between the open electrodes of the batteries but none at the terminals of the bulb. The "circuit" is not a circuit, it is open. Or you could consider it a circuit with an infinite resistance between the electrodes of the batteries. This also explains why there is no current in the circuit.

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It will not glow until the circuit is completed. The batteries are not connected so there is no completed path for the current. Connect the positive and negative terminals of the two batteries and then it will glow.

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  • $\begingroup$ Why do the cells need to be connected for current to flow? The Bulb is connected to a positive end and a negative end. $\endgroup$ – Hark Mar 6 '18 at 16:52
  • $\begingroup$ The circuit as drawn is an open circuit. Two of the battery terminals are not connected to anything. They need to be connected together or be connected to ground. Current needs a completed path to flow. Otherwise it would need to 'jump across' the space between the unconnected battery terminals, which it can not do (in the steady state). $\endgroup$ – user45664 Mar 6 '18 at 17:07
  • $\begingroup$ Why can't the current flow from the left cell to the right cell or vice-versa? $\endgroup$ – Hark Mar 6 '18 at 17:20
  • $\begingroup$ It needs to flow from the positive terminal of the left cell to the negative terminal of the right cell (where it has a path now), and then flow from the positive terminal of the right cell to the negative terminal of the left cell (where now it has no path). If you think of current as moving electrons, then the electrons need a conductor between the terminals to flow through. Otherwise charge would be accumulated somewhere and there is no capacitor (charge accumulator) in this circuit. $\endgroup$ – user45664 Mar 6 '18 at 17:36
  • $\begingroup$ The current flowing out of the battery must equal the current flowing in to the battery. see slideshare.net/HimanshuBatra2/circuit-laws-network-theorems --these are Kirchoff's circuit laws. $\endgroup$ – user45664 Mar 6 '18 at 17:46
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The circuit must be complete for the bulb to light, otherwise no current will flow. A current will flow for a very short period of time, but then a concentration of charge will form that will create a potential difference negating that potential difference from the batteries.

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