Your friends are installing a loft in their room and are using thin speaker
wires to provide power to an extra outlet. If they draw only a small amount
of current from the outlet, the voltage drop in each of the wires will remain
small. Why? - ANS ✓The voltage drop is directly proportional to the current.
Ohm's law states that the potential difference (voltage drop) is directly
proportional to the current.
A particular lightbulb is designed to consume 40 W when operating on a
car's 12-V DC electric power. If you supply that bulb with 12-V AC power
from a transformer, how much power will it consume? - ANS ✓40 W.
The lightbulb will consume the same amount of power it was designed to
consume. The average power of an AC source is the same power provided
as a DC source.
Your toaster consumes 800 W when operating on 120-V AC electric power.
If your rugby team is camping and all of you string together flashlight
batteries to supply that toaster with 120-V DC electric power, how much
power will it consume? - ANS ✓800 W.
PHY 102
, 2
PHY
The toaster will consume the same amount of power it was designed to
consume. The average power of an AC source is the same power provided
as a DC source.
To read the magnetic strip on an ID or credit card, you must swipe it
quickly past a tiny coil of wire. Why must the card be moving for the coil
system to read it? - ANS ✓A moving magnet will induce a current in the coil so
that the magnetic strip can be read.
Only moving magnets or a changing magnetic field will produce the electric
field necessary to push currents through the coil.
If the primary coil of a transformer has 200 turns and is supplied with 120-
V AC power, how many turns must the secondary coil have to provide 12-V
AC power? - ANS ✓20 turns.
secondary voltage = primary voltage · (secondary turns / primary turns)
The primary coil of a transformer makes 240 turns around the iron core,
and the secondary coil of that transformer makes 80 turns. If the primary
voltage is 120-V AC, what is the secondary voltage? - ANS ✓40-V AC.
PHY 102
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller DoctorKen. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
