η = 13.8 lm/W. The luminous efficacy of a incandescent lightbulb that produces 830 lumens and consumed a power of 60 W is 13.8 lm/W.
The luminous efficacy of a light source is the relationship between the luminous flux (in lumens) emitted by a light source and the power (in watts). The luminous efficacy of a light source or luminous efficiency measures the part of electrical energy that is used to illuminate and is obtained by dividing the luminous flux emitted by the electrical power consumed. Luminous efficiency is expressed in lumens per watt (lm / W). It is given by the relation:
η = F / P. Where F is the luminous flux, and P is the power consumed by the light source.
The efficacy of a 60.0 W incandescent lightbulb that produces 830 lm is:
η = 830 lm / 60 W
η = 13.8 lm/W
Answer:
C. total heat energy of the substance has increased
Explanation:
This is because when there is a change in temperature, the heat energy of a substance either increases or decreases. If the temperature increases, its heat energy increases and if its temperature decreases, its heat enery decreases.
Answer:
The angular displacement of each wheel is 269.92 rad
Explanation:
Given:
Angular acceleration 
Time to pass cyclist 
s
Angular velocity 
According to the equation of kinematics,
For finding angular displacement,
Where 
angular displacement,
rad
Therefore, the angular displacement of each wheel is 269.92 rad
Answer:
B) 15.5 m/s
Explanation:
r = 60m
μs = 0.4
using the formula max V = √r*g*μs (flat roadway)
v = sqrt(60 * 10 * 0.4)
v = 15.5 m/s
Answer:
93.125 × 10^(19)
Explanation:
We are told the asteroid has acquired a net negative charge of 149 C.
Thus;
Q = -149 C
charge on electron has a value of:
e = -1.6 × 10^(-19) C
Now, for us to determine the excess electrons on the asteroid, we will just divide the net charge in excess on the asteroid by the charge of a single electron.
Thus;
n = Q/e
n = -149/(-1.6 × 10^(-19))
n = 93.125 × 10^(19)
Thus, it has 93.125 × 10^(19) more electrons than protons
