# Tag Info

### What happens if ONLY one terminal of a cell is connected to a piece of conducting wire?

Consider a cell of emf $\epsilon$, and negligible internal resistence.Then, suppose I connect one end conducting wire of negligible resistence to the positive terminal of the battery while leaving the ...
• 68.9k

### How to apply Kirchhoff's rules in a circuit with Voltmeter?

An ideal voltmeter has no effect on the circuit, so Solve the circuit without the voltmeter connected. The voltmeter measures the difference between the nodes to which it connects.
• 5,488
Accepted

### Where is the excess energy going to when a solar inverter is operating a photovoltaic (PV) panel away from the maximum power point (MPP)?

The answer is easier if you only consider a single cell, and apart from some details the same answer holds for an entire string of cells and then for an entire panel that consists of several strings. ...
• 36

### Why is mean free time inversely proportional to the electric field strength?

Keep in mind that that there is more going on, and that thinking about electrons as a gas is going to have limitations. As you increase the electric field and the electrons accelerate, if the mean ...
• 1,561
Accepted

### Electric current through the resistor of an AC $(L)RC$-circuit

Is the current through the resistor really always in phase with 𝑈? Ideally, yes. What power will the resistor really dissipate? The power associated with the current through the resistor alone. ...
• 5,488
Accepted

### What causes the behavior of the increasing transient current in a circuit with an ohmic resistor?

When the switch is closed the electric field produced by the battery, and the force it applies to the electrons, appear almost instantaneously throughout the resistive circuit (near the speed of light)...
• 57.2k

### Connecting only one plate of the capacitor to the positive terminal of a battery

Connecting one plate to the positive terminal of a battery and leaving the other plate disconnected will simply result in the existing free charge (electrons) on each of the two plates to ...
• 57.2k
Accepted

### Kirchoff analysis in faraday law for RL circuit

This is a still from Walter Lewin's video 8.02x - Lect 20 - Inductance, RL Circuits, Magnetic Field Energy. He evaluates $\displaystyle \int \vec{E} \cdot d\vec{l}$ for each of the three circuit ...
• 79.6k
1 vote
Accepted

### Solving an ODE numerically with different units

When changing the units by scaling, we generally want to write our formulae as a unitless number (which is what changes in the simulation) and a constant unit scale (which does have to be consistent ...
• 24.7k
1 vote
Accepted

### Why doesn't energy supply rate equal the dissipation rate for electrical energy transmissions?

The energy that is supplied by the generator goes to energy dissipated by the transmission wires but also (usually mostly) by the load at the other end of the transmission lines. Does that explain ...
• 7,529
1 vote
Accepted

### Applying KVL to a circuit with only a battery and a capacitor

If you model a battery as an ideal voltage source in series with an internal resistance then you have a standard RC circuit which charges the capacitor with a time constant of $\tau=RC$. If you wish ...
• 68.9k
1 vote

### What causes the behavior of the increasing transient current in a circuit with an ohmic resistor?

The answers of both @Bob D and @niels nielson are perfectly correct within the framework of circuit theory, where the current is the same everywhere in the circuit, whether time-varying or not. ...
• 947
1 vote

### What causes the behavior of the increasing transient current in a circuit with an ohmic resistor?

For the transient current to overshoot its steady-state value mathematically requires the presence of capacitance or inductance (or both) in the circuit. With only an (ideal, ohmic) resistor in it, ...
1 vote

### Calculating the rate of heat dissipation in a tungsten filament

We have the connection between the filament temperature $T$ and its resistivity $\rho(T)$ (namely, the temperature-dependent resistivity of pure tungsten), so if we model the filament temperature, we ...
• 14.5k
1 vote
Accepted

### An electric motor operates on a 50 V supply and a current of 12 A. If the efficiency of the motor is 30% what is the resistance of winding of motor?

Energy losses due to current flowing in an element of wire are given by the formula $$RI^2$$ where $R$ is resistance of the wire element and $I$ is current there. The formula $$\frac{V^2}{R}$$ is ...
• 28.9k
1 vote

### An electric motor operates on a 50 V supply and a current of 12 A. If the efficiency of the motor is 30% what is the resistance of winding of motor?

Your second equation is based on $V=IR$ where $V$ is the supply voltage. But the supply voltage is the total voltage across the motor, which, in the case of induction motors, is modeled as a ...
• 57.2k
1 vote

### KVL in short circuit with 0 resistance

This is a self-contradictory circuit model. Remember, the things that we put in a circuit diagram are there to represent real objects. As such, they are generally approximations and the real behavior ...
• 68.9k
1 vote

### Derivation of the potential difference across a resistor

I think you're making this far too difficult. Ohm's law is a relation between quantities, not a definition of cause and effect. If you apply a voltage to a resistor, Ohm's law tells you the current. ...
• 5,488
1 vote

### What happens if ONLY one terminal of a cell is connected to a piece of conducting wire?

Usually by "current", we're talking about large-scale, steady-state bulk flows of charge. These are easy to analyze with concepts like Ohm's law and others. But transitory charge movement ...
• 34.6k
1 vote

### Connecting only one plate of the capacitor to the positive terminal of a battery

The answer is that there is a very tiny capacitance between the "dangling" lead of the capacitor and the other terminal of the battery. The full circuit is then Batter -> real capacitor -&...
• 9,458

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