Answer:
120 volts is the root mean square (rms) average of the voltage as it varies with time.
Explanation:
A. The average voltage over many weeks of time (false)
Reason: Average AC voltage over one cycle is cycle (from one peak to other) is zero and so over many weeks of time it is zero.
B. The peak voltage from an AC wall receptacle (false)
Reason: The peak voltage of an AC source in North America is zero.
C. The arithmetic mean of the voltage as it varies with time (false)
Reason: Arithmetic mean AC voltage over one cycle is cycle (from one peak to other) is zero and so over many weeks of time it is zero.
D. One-half the peak voltage (false)
Peak voltage =170 Volts
One-half the peak voltage = 85 volts
E. The root mean square (rms) average of the voltage as it varies with time (True)
Reason:
The peak voltage and root mean square voltage are related by:
Average value of voltage over one cycle is zero, so instead of calculating average voltage for AC peak voltage is first squared and the mean is calculated.
Answer:
When a polythene rod is rubbed with a duster, the friction causes electrons to gain energy. Electrons gain enough energy to leave the atom and 'rub off' onto the polythene rod. The polythene rod has gained electrons, giving it a negative charge.
Explanation:
Hope it helps
Answer:
8.33*10^-16 Watt
Explanation:
Given that
Length of the rod, l = 2 m,
Area of the rod, A = 2 x 2 mm² = 4*10^-6 m²
resistivity of the rod, p = 6*10^-8 ohm metre,
Potential difference of the rod, V = 0.5 V
Let R be the resistance of the rod, then
R = p * l / A
R = (6*10^-8 * 2) / (4*10^-6)
R = 3*10^14 ohm
Heat generated per second = V² / R Heat = (0.5)² / (3*10^14)
Heat = 0.25 / 3*10^14
Heat = 8.33*10^-16 Watt
Therefore, the rate at which heat is generated is 8.33*10^-16 Watt
The correct answer is <u>B. Where crust is destroyed.</u>
Answer:
There is absolutely No relationship between the weight of an object (which is constant) and the frictional force. If a block is sliding on a surface, that surface will be exerting a force on the block. That force can be resolved into a component parallel to the surface (which we call the frictional component), and a component perpendicular to the surface (called the normal component). For many situations, we find experimentally that the frictional component is approximately proportional to the normal component. The frictional component divided by the normal component is defined to be a quantity called the coefficient of kinetic or sliding friction. The coefficient of kinetic friction obviously depends on the nature of the surfaces involved. The normal component on an object can be decreased if you pull in the direction of the normal component (the weight does not change). However pulling this way on the object not only decreases the normal component, but it also decreases the frictional component since they are proportional. This is why it is easier to slide something if you pull up on it while you push it. If you push down, the normal and frictional components increase so it is harder to slide the object. The weight of an object is the downward force exerted by Earth’s gravity on that object, and it does not change no matter how you push or pull on the object.
