Very basic circuits 1 question. Charge and current

In summary, the charge q(t) flowing through a device with a current of 20 cos(10t + π/6)μA and an initial charge of 2 μC can be found by taking the integral of the current function and adding the initial charge. The correct solution is (2sin(10t+π/6)+1)μC, as it gives the correct answer when t = 0 is plugged in.
  • #1
A.J.710
53
1

Homework Statement


Find the charge q(t) flowing through a device if the current is: 20 cos(10t + π/6)μA, q(0) = 2 μC

Homework Equations


∫ i(t)dt +q(0)

The Attempt at a Solution


I am studying for a test by working all the problems I can and then looking at the solutions manual. The solutions manual says the answer is (2sin(10t+π/6)+1)μC. I got the same thing except +2 at the end since q(0) is 2. It's really bugging me that I can't figure out why. Can anyone please explain?
 
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  • #2
A.J.710 said:
The solutions manual says the answer is (2sin(10t+π/6)+1)μC. I got the same thing except +2 at the end since q(0) is 2.
If you plug in t = 0 to your solution and the manual's, which one gives the correct answer?
 
  • #3
Doc Al said:
If you plug in t = 0 to your solution and the manual's, which one gives the correct answer?
Ahh, got it now. Thank you. I didn't realize that's what it meant. I was just adding the q(0) but I didn't realize until you pointed it out that the entire function in itself is q.
 

Related to Very basic circuits 1 question. Charge and current

1. What is charge?

Charge is a fundamental property of matter that refers to the amount of electrical energy an object possesses. It can be positive or negative and is measured in units of coulombs (C).

2. What is current?

Current is the flow of electric charge through a circuit or medium. It is measured in units of amperes (A) and is represented by the symbol "I".

3. What is the relationship between charge and current?

The relationship between charge and current is described by Ohm's Law, which states that current (I) is equal to the ratio of voltage (V) and resistance (R) in a circuit. In other words, current is directly proportional to voltage and inversely proportional to resistance.

4. How is charge conserved in a circuit?

Charge is conserved in a circuit through the principle of conservation of charge, which states that charge can neither be created nor destroyed. This means that the total charge entering a circuit must be equal to the total charge leaving the circuit.

5. What is the difference between AC and DC circuits?

AC (alternating current) circuits have a constantly changing direction of current flow, while DC (direct current) circuits have a constant direction of current flow. AC circuits are typically used for large-scale power distribution, while DC circuits are used for smaller, more specialized applications.

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