Answer:
d. boost frequencies below 80 Hz.
Explanation:
Low frequency sound appear to be soothing to mind. It is called bass . bass instruments play low frequency notes. But to produce low frequency note , the size of musical instruments have to be increased which increases its cost.
Any instrument which boosts low frequency are therefore costly . They are accompanied by air amplifier.
Answer:
option C
Explanation:
the correct answer is option C.
All the activity such as Radioactive isotopes, differentiation of Earth’s iron core, gravity-driven compression,and meteoric bombardment will make the earth hotter than what it is at present.
Radioactive isotope whose nuclei are unstable dissipate excess energy.
Differentiation of iron core means formation of into layer which includes iron.
meteorite bombardment will affect the atmosphere of the earth which protect harmful radiation.
All these activity will make earth hotter
Answer:
Magnetic field experienced = 4.5 × 10⁻⁴ T
Explanation:
The magnetic field around an infinite straight current-carrying wire at a distance r from the wire is given by
B = (μ₀I)/(2πr)
B = ?
I = 20 KA = 20000 A
r = 8.9 m
μ₀ = magnetic permeability = 1.257 × 10⁻⁶ T.m/A
B = (1.257 × 10⁻⁶ × 20000)/(2π×8.9) = 4.5 × 10⁻⁴ T
Metallic bondings occurs between metals (the metals delocalize their valance electrons and the attraction occurs between the now positive metals and the de localized sea of electrons)
Rate of speed (3 m/s north is three miles per second north, so it's a rate of speed)
