Start learning this material nowGet Started
STP Waves & Rad 122 cards
Tagged as: travel, nursing, earth, geography, physics, economics, astronomyCopy deck
Alpha (α), absorbed by paper, range about 10cm. Beta (β), absorbed by up to 1cm Al, or 2-3mm of Pb, range about 1m. Gamma (γ) absorbed by thick lead (several cm) or thick concrete (more than 1m), unlimited range.
Alpha, then beta, then gamma.
Alpha is positive so it is attracted to the negative electrode. Beta is negative so it is attracted to the positive electrode. Gamma is not affected.
Alpha and beta, (gamma is not affected).
Gamma, with a very short half life. It can easily escape to be detected outside the body.
When rolling thin sheets (e.g. paper, rubber), which radioactive source is the best to use to control the thickness?
Beta. Less beta detected = too thick, more = too thin. (alpha would not pass through and gamma would not change)
Alpha. It is the most ionising and is easily absorbed. Beta and gamma are less likely to be absorbed.
Alpha. It can not penetrate the body unlike beta and gamma.
The time taken for the number of nuclei in an isotope to halve.
If there are 1000 unsatble nuclei in a substance with a half-life of 10 days, how many will be left after 30 days?
30 days = 3 x half-life. 1000 to 500 (1st half-life), 500 to 250 (2nd half-life), 250 to 125 (3rd half-life). So there will be 125 left.
Cancer, the larger the dose of radiation, the greater the risk of cancer.
They give out light.
Visible light or other EM radiation like radio waves or X-rays.
Reflecting uses mirrors and refracting uses lenses to produce sharper more detailed images. Both can only be used at night.
Most have a parabolic dish to reflect the long radio waves to a receiver which can amplify the signal.
In space as this stops atmospheric interference (clouds, poor weather, light pollution etc). If on Earth, they are put on top of mountains in remote areas with low level pollution.
Observed wavelengths and observed frequency.
Red-shift. This suggests the Universe is expanding.
The universe is expanding after exploding suddenly from a very small point. Space, time and matter were created in the big bang.
Red-shift and background microwave radiation discovered in 1965.
Red-shift observed from Earth.
Ready to start studying? Once you get going, we'll notify you when it is time to study next.