# Horrible Homework question on alternating currents

• Sofie1990
In summary: You calculated T = 3.0 ms. But you need T in seconds. 1.0 ms = 1.0E-3 seconds. So 3.0 ms = 3.0E-3 seconds.f = 1/3.0E-3 = 333 Hz.So your answer is correct. :approve:In summary, the oscilloscope settings were given and students were asked to determine the peak voltage and r.m.s voltage of an a.c source connected to a resistor, as well as the time period and frequency of the a.c signal. The peak voltage was found to be 8.0v, the r.m.s voltage was 5.7v, the time period
Sofie1990

## Homework Statement

An alternating current source is connected to a resistor to form a complete circuit. The oscilloscope settings are: Y sensitivity 4.0v per division
Time base 1.0ms per division
(i)determine peak voltage of the a.c source
(ii)Hence calculate the r.m.s voltage
(iii)Determine the time period of the a.c signal
(iv)Hence calculate the frequency of the a.c signal

The oscilliscope trace was 4 divisions from peak to trough and 3 divisions for 1 complete wave.

## The Attempt at a Solution

(i) 8.0v
(ii) 5.7v
(iii) 3.0ms
(iv) could not work out

Sofie1990 said:

## Homework Statement

An alternating current source is connected to a resistor to form a complete circuit. The oscilloscope settings are: Y sensitivity 4.0v per division
Time base 1.0ms per division
(i)determine peak voltage of the a.c source
(ii)Hence calculate the r.m.s voltage
(iii)Determine the time period of the a.c signal
(iv)Hence calculate the frequency of the a.c signal

The oscilliscope trace was 4 divisions from peak to trough and 3 divisions for 1 complete wave.

## The Attempt at a Solution

(i) 8.0v
So far so good.

But just to be nit-picky, I've never liked the use of the phrase "peak voltage" to describe the amplitude of an AC signal. It's too easily confused with "peak-to-peak." But I guess you have no choice in that, given your coursework. The term "peak voltage" is standard terminology even if I don't like it. Your answer is correct as it is.

(ii) 5.7v
I'm not sure how many significant figures you are supposed to use, but with only two significant figures, your answer is correct.
(iii) 3.0ms
Correct.
(iv) could not work out
The frequency, f, of a signal is the inverse of its period, T. In other words, f = 1/T.

If T is measured in seconds, than f is measured in Hertz (Hz).

## 1. What is an alternating current (AC)?

An alternating current is a type of electricity that changes direction regularly, usually at a specific frequency. This is in contrast to direct current (DC) which only flows in one direction.

## 2. How is alternating current generated?

Alternating current is typically generated by an electrical generator, which converts mechanical energy into electrical energy. This mechanical energy can come from various sources, such as steam, water, or wind.

## 3. What are the advantages of alternating current?

One of the main advantages of alternating current is that it can be easily transformed to different voltages, making it more efficient for long-distance transmission. It also allows for the use of devices such as transformers and motors, which are not possible with direct current.

## 4. How does alternating current affect our daily lives?

Alternating current is the most commonly used type of electricity in homes and businesses. It powers our lights, appliances, and electronic devices, making it an integral part of our daily lives.

## 5. Are there any safety concerns with alternating current?

While alternating current can be dangerous if mishandled, it is generally considered safe for everyday use. However, it is important to follow proper safety precautions when working with electricity, such as using insulated tools and turning off power before making any repairs or changes.

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