Physics Revision Questions
... An alternating current flows into the primary coil. This makes a magnetic field in the core. The magnetic field changes direction 100 times a second. The changing magnetic field induces a current in the secondary coil. The induced current is alternating too. It improves efficiency by reducing heat l ...
... An alternating current flows into the primary coil. This makes a magnetic field in the core. The magnetic field changes direction 100 times a second. The changing magnetic field induces a current in the secondary coil. The induced current is alternating too. It improves efficiency by reducing heat l ...
A Photographic Method for Panoramic Sequence with a Regular
... After the film is developed and the photoprint is enlarged into a full frame, the center of the photoprint can be obtained by intersecting the two diagonal lines. However, when the film was developed in a regular photo shop, the edges are trimmed and one cannot estimate the center precisely. Moreove ...
... After the film is developed and the photoprint is enlarged into a full frame, the center of the photoprint can be obtained by intersecting the two diagonal lines. However, when the film was developed in a regular photo shop, the edges are trimmed and one cannot estimate the center precisely. Moreove ...
Time traveller – Activity
... large. For example, the distance from the star Sirius to Earth is 84 320 000 000 000 km. This distance is too large for most people to imagine or understand. There are ways to make such large numbers more manageable. For instance, it is easier to understand and work with 15 years than it is with 5 4 ...
... large. For example, the distance from the star Sirius to Earth is 84 320 000 000 000 km. This distance is too large for most people to imagine or understand. There are ways to make such large numbers more manageable. For instance, it is easier to understand and work with 15 years than it is with 5 4 ...
Volume 1 (Issue 3), March 2012
... Cycles of the Sun, Earth and Planets Our Sun, the nearest star, rises and sets every day. This motion of the Sun in the sky occurs because of the rotation of the Earth on its axis. The Earth completes one rotation in 24 hours and takes approximately 365.25 days to complete one revolution around the ...
... Cycles of the Sun, Earth and Planets Our Sun, the nearest star, rises and sets every day. This motion of the Sun in the sky occurs because of the rotation of the Earth on its axis. The Earth completes one rotation in 24 hours and takes approximately 365.25 days to complete one revolution around the ...
Astrophotography
Astrophotography is a specialized type of photography for recording images of astronomical objects and large areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum light photons over these long periods of time. Photography revolutionized the field of professional astronomical research, with long time exposures recording hundreds of thousands of new stars and nebulae that were invisible to the human eye, leading to specialized and ever larger optical telescopes that were essentially big cameras designed to collect light to be recorded on film. Direct astrophotography had an early role in sky surveys and star classification but over time it has given way to more sophisticated equipment and techniques designed for specific fields of scientific research, with film (and later astronomical CCD cameras) becoming just one of many forms of sensor.Astrophotography is a large sub-discipline in amateur astronomy where it is usually used to record aesthetically pleasing images, rather than for scientific research, with a whole range of equipment and techniques dedicated to the activity.