# Tagged Questions

Devices to store chemical energy and convert it to electrical energy.

554 views

### Why the EMF of a battery doesn't depend on distance between the two electrodes?

I have read that resistance of a conductor is directly proportional to its length. So, the EMF of a conductor (electrolyte of battery) should increase with increase in length/distance between the ...
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### Why would a series of cells not be suitable for a car battery? [closed]

A car battery needs to supply a current of $200A$ to turn over the starter motor. Explain why a battery made of a series of cells would not be suitable for a car battery. My thinking: I'm thinking ...
5k views

### How can a battery charge up another battery to a higher percentage?

Say I have my phone on 5% and a large battery pack on 35% and I charge the phone. By the end the phone is on 100% and the pack is on 12%. How can the battery pack charge the phone up to a higher ...
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### Work done by the battery in series with capacitor with changing dielectric

If we have a battery with voltage $V$ connected in series with a parallel-plate capacitor of capacitance $C$ with dielectric $\epsilon$,and then we pull the dielectric out, the infinitesimal work done ...
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### Why does a battery die more quickly when more resistors are added to the circuit?

I will be explaining what I think: A battery acts like a pump which provides energy to do work on negative charges to move them towards the negative terminal, and hence creating an electric field. ...
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### Change in the EMF of the battery while charging

While charging a battery current is passed from A to B. We form the equation as follows- $$V_A - E - i_r= V_B$$ If the battery is discharged, how can we consider the EMF of the battery in this ...
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### Li-ion Battery charging

Why are constant current mode and constant voltage mode needed when charging Li-ion batteries? Why do we apply saturation charge even after the cell voltage reaches 4.2V? What exactly is 'I-sense' in ...
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### Circuit theory paradox - Unexpected results [closed]

I recently studied capacitors and found out that there is something called 'ideal circuit paradox'. Searching Google I found that one can cannot find the potential difference between two points in a ...
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### DC can be stored in batteries, while we cannot store AC [closed]

i have heard that direct current can be stored in batteries, but we can not store alternating current. is it true? if yes, then why?
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### Charging of a battery (reversing of polarity)

I wanted to know that how can we charge a battery using another higher voltage DC supply? I got a question that there is a 12 volt battery with an internal resistance 3ohm Connected with a 100 V DC ...
1k views

### Can a battery charger be too powerful for a rechargeable battery?

I got the impression that a regular iPhone charger can charge the iPhone and the iPhone won't become too hot while charging, and the charging time is standard, but if using the 10W iPad charger to ...
378 views

### How is Capacitance affected by a seperation distance and with or without a battery?

The questions specifically says this : A parallel-plate capacitor initially has capacitance $C$. The distance between the plates is then doubled, with a $9.0V$ battery connected. The battery is then ...
34 views

### Is a real voltaic cell always schematically equivalent to an ideal battery and a resistor?

In the diagram I have attached, the top circuit is the schematic equivalent I am trying to use to model the middle circuit which uses real voltaic cells (that have internal resistance). I am not sure ...
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### Is the $C$ rating of a battery a measure of Capicitance or Charge?

I have become confused as to the meaning of what a C rating of a battery means. My understanding is that because a C rating is measured in milli-ampere hours the units should cancel to be a unit of ...