Explanation

In oscillatory motion, such as that of an oscillating charge, velocity varies continuously.

It is zero at extreme positions and maximum at the mean position, so it is changing.

Explanation

In Photosystem II (PSII), chlorophyll a is present in the reaction center called P680.

P680 absorbs light most efficiently at 680 nm, which lies in the red region of the visible spectrum.

Explanation

Deft means کچھ کرنے میں مہارت اور چالاکی کا مظاہرہ کرنا

Skilful means مہارت حاصل کرنا یا دکھانا

Explanation

Deliberately means جان بوجھ کر یا مقصد کے مطابق کچھ کرنا ، حادثے سے نہیں

Purposely means منصوبہ بند یا شعوری عمل کے خیال کو پہنچانا

Explanation

Total internal reflection occurs when light travels from a denser to a rarer medium, and the angle of incidence exceeds the critical angle.

At this point, light is completely reflected back into the denser medium.

Explanation

The maximum kinetic energy (K.E.) of photoelectrons depends on the frequency of the incident light, not its intensity. 

According to Einstein's photoelectric equation:

K.E. = hf - φ

where hf is the energy of the photon, which depends on its frequency (f).

Explanation

A solid-state detector is essentially a PN junction that detects radiation by generating charge carriers.

Incoming particles or photons produce electron-hole pairs in the depletion region of the PN junction.

Explanation

The Pfund series of hydrogen spectral lines occurs when electrons fall to the n = 5 energy level from higher levels.

These transitions emit radiation in the infrared (IR) region of the electromagnetic spectrum.

Explanation

Aluminum sulphate (also called alum) is a common coagulant used to purify potable water by causing suspended impurities to clump together and settle.

It helps remove particles, bacteria, and organic matter by forming flocs during the coagulation-flocculation process.

Explanation

Device means ایک مخصوص مقصد کے لئے تیار کردہ ایک آلہ یا سامان

Machine means عین مطابق کام کے لئے استعمال ہونے والے ایک آلے کے لئے ، جیسے پیمائش