Current versus voltage, Very Easy (but stuck)

In summary, the problem gives a graph of Emf versus time in a circuit with a capacitor and voltage source. The task is to draw the time dependence of the current in the circuit. The graph shows a trapezoid shape with a positive slope starting at Emf=0 t=0, reaching t1 where the slope becomes 0, and then transitioning to a negative slope until t4 where it reaches Emf=0. There is no resistor mentioned in the circuit, but adding one would not change the shape of the current graph. The relationship between emf, capacitance, and current can be described by two equations.
  • #1
pynergee
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0

Homework Statement


The problem gives a graph of Emf versus time, in a circuit consisting of capacitor C and voltage source e. It asks to draw the time dependence of the current I in the circuit.


Homework Equations


The graph looks like a trapezoid, positive slope starting at Emf=0 t=0, getting to t1 where the slope becomes 0, until t2, where it becomes a negative slope, and travels to t4 where it reaches Emf = 0


The Attempt at a Solution


I know for Ohms law it states V = I/R, but there isn't a Resistor in the circuit given. Would this just show that the current graph should look exactly the same as voltage graph?

Please help, thank you.
 
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  • #2
You can put a resistor in (after all the leads always have some resistance), but this will not change what the drawing of the time dependence of the current looks like.

How about some equations to begin with? How are emf, capacitance and current related? You need two equations for starters.
 
  • #3


I would approach this problem by considering the components and principles at play in the circuit. While Ohm's law is a fundamental equation, it only applies to circuits that contain resistors. In this case, the circuit consists of a capacitor and a voltage source. Therefore, we must consider the relationship between current and voltage in a circuit with these components.

In a circuit with a capacitor, the current is related to the rate of change of the voltage across the capacitor. This means that as the voltage increases, the current will also increase. However, once the voltage reaches a certain point, the current will start to decrease, and eventually reach 0. This is because the capacitor becomes fully charged and can no longer allow current to flow.

In this specific case, the voltage graph has a trapezoidal shape, which indicates a gradual increase and decrease in voltage. This means that the current graph will also have a similar shape, with a gradual increase until the capacitor is fully charged, followed by a gradual decrease until the voltage reaches 0 again. The specific shape and timing of the current graph will depend on the values of the components in the circuit.

In summary, the current graph will not look exactly the same as the voltage graph, but it will have a similar shape and timing. This is due to the relationship between current and voltage in a circuit with a capacitor and voltage source. I hope this helps to clarify the problem.
 

1. What is the difference between current and voltage?

Current refers to the flow of electric charge through a circuit, while voltage is the measure of the potential energy that drives this flow. In simpler terms, current is the amount of electricity moving through a circuit, while voltage is the force that makes it move.

2. How are current and voltage related?

Current and voltage are directly proportional to each other according to Ohm's Law. This means that as voltage increases, current also increases, and vice versa. However, the relationship between them can be influenced by factors such as resistance and capacitance.

3. Which one is more dangerous, high current or high voltage?

Both high current and high voltage can be dangerous, but in different ways. High current can cause severe burns and muscle contractions, while high voltage can result in electric shock and damage to internal organs. The level of danger also depends on the duration of exposure and the path of the current or voltage through the body.

4. How do we measure current and voltage?

Current is measured in amperes (A) using an ammeter, while voltage is measured in volts (V) using a voltmeter. Both devices are connected in series with the circuit and have very low resistance to avoid altering the values being measured.

5. What is the difference between AC and DC current and voltage?

AC (alternating current) and DC (direct current) refer to the direction of flow of electric charge. In AC, the direction of current changes periodically, while in DC, the direction remains constant. Similarly, AC voltage changes direction periodically, while DC voltage remains constant. Most household appliances operate on AC, while batteries provide DC power.

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