<u>Answer</u>
1/4
<u>Explanation</u>
half life = 15 years
decay period = 30 years
The number of half-lives = 30 ÷ 15
= 2 half lives
1 ⇒(<em>after 1st half life</em>) ⇒ 1/2 ⇒ (<em>after 2nd half life</em>) ⇒ 1/4
The fraction that remained is 1/4.
Blue because usually people will think the color of water is blue so it will match/blend more than red or green
Answer: 0.0054 s
Explanation:
There is an inverse relation between the frequency and the period of a wave (a sound wave in this case):
Where
Hence:
C. 7.8 hz I think! Hope this helped ☺️
The electron’s speed when it reaches the positive plate is 2.65 X 10⁶m/s
<u>Explanation:</u>
Electric field strength, E = 20,000 N/C
Distance, x = 1 mm = 1 X 10⁻³m
Speed of the electron, s = ?
We know,
Charge of an electron, q = 1.602 X 10⁻¹⁹ C
So the force, F is
20000 N/C x 1.602 X 10⁻¹⁹ C = 3.2 X 10⁻¹⁵ Newtons
mass of electron is 9.1×10⁻³¹ kg
F = ma
a = 3.2 X 10⁻¹⁵ / 9.1 X 10⁻³¹ = 3.52 X 10¹⁵ m/s²
v = √(2ad) = √(2*3.52 X 10¹⁵ X 0.001) = 2.65 X 10⁶m/s
Therefore, the electron’s speed when it reaches the positive plate is 2.65 X 10⁶m/s