A pulsar is a rapidly rotating neutron star that emits radio waves.
Describe the formation of a neutron star from a massive star.
State one characteristic property of a neutron star.
A typical neutron star can be modelled as a sphere with mass M≈1.5×1030 kgM \approx 1.5 \times 10^{30}\,\text{kg}M≈1.5×1030kg and radius R≈12 kmR \approx 12\,\text{km}R≈12km.
Show that the average density of this neutron star is similar to the average density of an atomic nucleus.
An astronomer uses a radio telescope to observe a pulsar.
During one full rotation of the pulsar, the telescope receives a single radio pulse. This pulse is modelled as a symmetric triangular peak of power against time. The power rises linearly from 0 W0\,\text{W}0W at t=0t = 0t=0 to a peak of 6.0×10−22 W6.0 \times 10^{-22}\,\text{W}6.0×10−22W at t=4.0 mst = 4.0\,\text{ms}t=4.0ms, and then falls linearly back to 0 W0\,\text{W}0W at t=8.0 mst = 8.0\,\text{ms}t=8.0ms.
Calculate the total energy received by the telescope during one full rotation of the pulsar.
The collecting surface area of the telescope is 4000 m24000\,\text{m}^24000m2. The distance to the pulsar is 400 pc400\,\text{pc}400pc.
By assuming that the radio emission from the pulsar is emitted equally in all directions, estimate the total radio energy emitted by the pulsar during one full rotation. (Use 1 pc≈3.1×1016 m1\,\text{pc} \approx 3.1 \times 10^{16}\,\text{m}1pc≈3.1×1016m)
66 exam-style questions on OCR A A Level Physics Astrophysics and cosmology, covering Stars, Electromagnetic radiation from stars, and Cosmology. Each one has a worked solution and a mark scheme showing where the marks go.