(i) The circuit diagram is shown in figure. Total resistance, R = 1Ω + 2Ω = 3Ω Potential difference, V = 6 V Power used in 2Ω resistor = I2R = (2)2 x 2 = 8 W (ii) The circuit diagram for this case is shown : Power used in 2 resistor = v2R =422 = 8 W. Hence, in both the cases power remains same as 8WRead more
(i) The circuit diagram is shown in figure.
Total resistance, R = 1Ω + 2Ω = 3Ω
Potential difference, V = 6 V
Power used in 2Ω resistor = I2R = (2)2 x 2 = 8 W
(ii) The circuit diagram for this case is shown :
Power used in 2 resistor = v2R =422 = 8 W.
Hence, in both the cases power remains same as 8W.
Power of first lamp (P1) = 100 W Potential difference (V) = 220 V I=P/V= 100/220A= 0.455A Resistance of lamp 1= V/I= 220/(100/220)= 484ohm. Therefore, 𝐼2=𝑃2/𝑉=60/220A=0.273A So, the net current drawn from the supply is given by 𝐼=𝐼1+𝐼2=0.455+0.273=0.728 𝐴
Power of first lamp (P1) = 100 W
Potential difference (V) = 220 V
I=P/V= 100/220A= 0.455A
Resistance of lamp 1= V/I= 220/(100/220)= 484ohm.
Therefore,
𝐼2=𝑃2/𝑉=60/220A=0.273A
So, the net current drawn from the supply is given by
𝐼=𝐼1+𝐼2=0.455+0.273=0.728 𝐴
Energy consumed by an electrical appliance is given by the expression, H = Pt Where, Power of the appliance = P Time = t Energy consumed by a TV set of power 250 W in 1 h = 250 × 3600 = 9 × 105 J Energy consumed by a toaster of power 1200 W in 10 minutes = 1200 × 600 = 7.2× 105 J Therefore, the enerRead more
Energy consumed by an electrical appliance is given by the expression,
H = Pt
Where,
Power of the appliance = P
Time = t
Energy consumed by a TV set of power 250 W in 1 h = 250 × 3600 = 9 × 105 J
Energy consumed by a toaster of power 1200 W in 10 minutes = 1200 × 600
= 7.2× 105 J
Therefore, the energy consumed by a 250 W TV set in 1 h is more than the energy consumed by a toaster of power 1200 W in 10 minutes.
Rate of heat produced by a device is given by the expression for power as P = I2R Where, Resistance of the electric heater, R = 8 Ω Current drawn, I = 15 A P = (15)2 x 8 = 1800 J/s Therefore, heat is produced by the heater at the rate of 1800 J/s.
Rate of heat produced by a device is given by the expression for power as
P = I2R
Where,
Resistance of the electric heater, R = 8 Ω
Current drawn, I = 15 A
P = (15)2 x 8 = 1800 J/s
Therefore, heat is produced by the heater at the rate of 1800 J/s.
(i) The tungsten is used almost exclusively for filament of electric lamps because it has a very high melting point (3300°C). On passing electricity through tungsten filament, its temperature reaches to 2700°C and it gives heat and light energy without being melted. (ii) The conductors of electric hRead more
(i) The tungsten is used almost exclusively for filament of electric lamps because it has a very high melting point (3300°C). On passing electricity through tungsten filament, its temperature reaches to 2700°C and it gives heat and light energy without being melted.
(ii) The conductors of electric heating devices such as bread-toasters and electric irons, are made of an alloy rather than a pure metal because the resistivity of an alloy is much higher than that of pure metal and an alloy does not undergo oxidation (or burn) easily even at high temperature.
(iii) The series arrangement is not used for domestic circuits because in series circuit, if one electrical appliance stops working due to some defect, than all other appliances also stop working because the whole circuit is broken.
(iv) The resistance of a wire is inversely proportional to its area of cross-section, i.e., Resistance R ∝ (1/πr2). If the area of cross section of a conductor of fixed length is increased, then resistance decreases because there are more free electrons for movement in conductor.
(v) Copper and aluminium wires usually employed for electricity transmission because they have very low resistances. So, they do not become too hot on passing electric current.
To demonstrate hydrotropism in plants. Procedure : i. Plant a seedling in a vessel containing soil. ii. Adjacent to the seedling put a porous pot containing water. iii. Leave the set up for few days. Observation : iv. On examining the roots it is observed that the roots bend towards the source of waRead more
To demonstrate hydrotropism in plants.
Procedure :
i. Plant a seedling in a vessel containing soil.
ii. Adjacent to the seedling put a porous pot containing water.
iii. Leave the set up for few days.
Observation :
iv. On examining the roots it is observed that the roots bend towards the source of
water and do not grow straight.
result :
It confirms that plant shows hydrotropism as the roots bend towards the porous pot of
water. As hydrotropism is a plant growth response in which the direction of growth is
determined by a stimulus of gradient in water concentration.
Auxins are the plant hormones produces at the tip of a shoot and root. Auxins are present at the tip of tendrils. When tendrils are attached around any support their growth is slowed down as auxins are sensitive to touch. This make them move to the other side of the tip to get support this makes theRead more
Auxins are the plant hormones produces at the tip of a shoot and root. Auxins are present
at the tip of tendrils. When tendrils are attached around any support their growth is
slowed down as auxins are sensitive to touch. This make them move to the other side of
the tip to get support this makes the other side grow faster than the side of tendril in
contact with the support and the tendril bends towards the support.
Auxins and Gibberlins are the hormone responsible for the growth of plant. Auxins are responsible for the cell elongation in shoot and also regulates growth. Gibberlin is responsible for stem elongation and germination.
Auxins and Gibberlins are the hormone responsible for the growth of plant. Auxins
are responsible for the cell elongation in shoot and also regulates growth. Gibberlin is
responsible for stem elongation and germination.
Movement of leaves of the sensitive plant 1. It does not depend on the direction of stimulus applied. 2. Touch is the stimulus. 3. Caused by the sudden loss of water from the swellings at the base of leaves. 4. Occurs very fast Movement of a shoot towards light 1. Depends on the direction of stimulRead more
Movement of leaves of the sensitive plant
1. It does not depend on the direction of stimulus applied.
2. Touch is the stimulus.
3. Caused by the sudden loss of water from the
swellings at the base of leaves.
4. Occurs very fast
Movement of a shoot towards light
1. Depends on the direction of stimulus applied.
2. Light is the stimulus.
3. Caused by the unequal growth on the two sides of the shoot.
Plant hormones are the organic substances produces at certain sites of the plant and are translocated to other parts based on the requirement. Plant hormones help to coordinate growth, development and responses to the environment. Ex: Auxin’s Gibberlin’s, cytokines, abscisic acid and ethylene.
Plant hormones are the organic substances produces at certain sites of the plant and are
translocated to other parts based on the requirement. Plant hormones help to coordinate growth, development and responses to the environment. Ex: Auxin’s Gibberlin’s, cytokines, abscisic acid and ethylene.
Compare the power used in the 2 ohm resistor in each of the following circuits:
(i) The circuit diagram is shown in figure. Total resistance, R = 1Ω + 2Ω = 3Ω Potential difference, V = 6 V Power used in 2Ω resistor = I2R = (2)2 x 2 = 8 W (ii) The circuit diagram for this case is shown : Power used in 2 resistor = v2R =422 = 8 W. Hence, in both the cases power remains same as 8WRead more
(i) The circuit diagram is shown in figure.
Total resistance, R = 1Ω + 2Ω = 3Ω
Potential difference, V = 6 V
Power used in 2Ω resistor = I2R = (2)2 x 2 = 8 W
(ii) The circuit diagram for this case is shown :
Power used in 2 resistor = v2R =422 = 8 W.
Hence, in both the cases power remains same as 8W.
See lessTwo lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Power of first lamp (P1) = 100 W Potential difference (V) = 220 V I=P/V= 100/220A= 0.455A Resistance of lamp 1= V/I= 220/(100/220)= 484ohm. Therefore, 𝐼2=𝑃2/𝑉=60/220A=0.273A So, the net current drawn from the supply is given by 𝐼=𝐼1+𝐼2=0.455+0.273=0.728 𝐴
Power of first lamp (P1) = 100 W
Potential difference (V) = 220 V
I=P/V= 100/220A= 0.455A
Resistance of lamp 1= V/I= 220/(100/220)= 484ohm.
Therefore,
𝐼2=𝑃2/𝑉=60/220A=0.273A
So, the net current drawn from the supply is given by
See less𝐼=𝐼1+𝐼2=0.455+0.273=0.728 𝐴
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Energy consumed by an electrical appliance is given by the expression, H = Pt Where, Power of the appliance = P Time = t Energy consumed by a TV set of power 250 W in 1 h = 250 × 3600 = 9 × 105 J Energy consumed by a toaster of power 1200 W in 10 minutes = 1200 × 600 = 7.2× 105 J Therefore, the enerRead more
Energy consumed by an electrical appliance is given by the expression,
H = Pt
Where,
Power of the appliance = P
Time = t
Energy consumed by a TV set of power 250 W in 1 h = 250 × 3600 = 9 × 105 J
Energy consumed by a toaster of power 1200 W in 10 minutes = 1200 × 600
= 7.2× 105 J
Therefore, the energy consumed by a 250 W TV set in 1 h is more than the energy consumed by a toaster of power 1200 W in 10 minutes.
See lessAn electric heater of resistance 8 W draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Rate of heat produced by a device is given by the expression for power as P = I2R Where, Resistance of the electric heater, R = 8 Ω Current drawn, I = 15 A P = (15)2 x 8 = 1800 J/s Therefore, heat is produced by the heater at the rate of 1800 J/s.
Rate of heat produced by a device is given by the expression for power as
P = I2R
Where,
Resistance of the electric heater, R = 8 Ω
Current drawn, I = 15 A
P = (15)2 x 8 = 1800 J/s
Therefore, heat is produced by the heater at the rate of 1800 J/s.
See lessExplain the following
(i) The tungsten is used almost exclusively for filament of electric lamps because it has a very high melting point (3300°C). On passing electricity through tungsten filament, its temperature reaches to 2700°C and it gives heat and light energy without being melted. (ii) The conductors of electric hRead more
(i) The tungsten is used almost exclusively for filament of electric lamps because it has a very high melting point (3300°C). On passing electricity through tungsten filament, its temperature reaches to 2700°C and it gives heat and light energy without being melted.
See less(ii) The conductors of electric heating devices such as bread-toasters and electric irons, are made of an alloy rather than a pure metal because the resistivity of an alloy is much higher than that of pure metal and an alloy does not undergo oxidation (or burn) easily even at high temperature.
(iii) The series arrangement is not used for domestic circuits because in series circuit, if one electrical appliance stops working due to some defect, than all other appliances also stop working because the whole circuit is broken.
(iv) The resistance of a wire is inversely proportional to its area of cross-section, i.e., Resistance R ∝ (1/πr2). If the area of cross section of a conductor of fixed length is increased, then resistance decreases because there are more free electrons for movement in conductor.
(v) Copper and aluminium wires usually employed for electricity transmission because they have very low resistances. So, they do not become too hot on passing electric current.
Design an experiment to demonstrate hydrotropism.
To demonstrate hydrotropism in plants. Procedure : i. Plant a seedling in a vessel containing soil. ii. Adjacent to the seedling put a porous pot containing water. iii. Leave the set up for few days. Observation : iv. On examining the roots it is observed that the roots bend towards the source of waRead more
To demonstrate hydrotropism in plants.
See lessProcedure :
i. Plant a seedling in a vessel containing soil.
ii. Adjacent to the seedling put a porous pot containing water.
iii. Leave the set up for few days.
Observation :
iv. On examining the roots it is observed that the roots bend towards the source of
water and do not grow straight.
result :
It confirms that plant shows hydrotropism as the roots bend towards the porous pot of
water. As hydrotropism is a plant growth response in which the direction of growth is
determined by a stimulus of gradient in water concentration.
How do auxins promote the growth of a tendril around a support?
Auxins are the plant hormones produces at the tip of a shoot and root. Auxins are present at the tip of tendrils. When tendrils are attached around any support their growth is slowed down as auxins are sensitive to touch. This make them move to the other side of the tip to get support this makes theRead more
- Auxins are the plant hormones produces at the tip of a shoot and root. Auxins are present
See lessat the tip of tendrils. When tendrils are attached around any support their growth is
slowed down as auxins are sensitive to touch. This make them move to the other side of
the tip to get support this makes the other side grow faster than the side of tendril in
contact with the support and the tendril bends towards the support.
Give an example of a plant hormone that promotes growth.
Auxins and Gibberlins are the hormone responsible for the growth of plant. Auxins are responsible for the cell elongation in shoot and also regulates growth. Gibberlin is responsible for stem elongation and germination.
Auxins and Gibberlins are the hormone responsible for the growth of plant. Auxins
See lessare responsible for the cell elongation in shoot and also regulates growth. Gibberlin is
responsible for stem elongation and germination.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Movement of leaves of the sensitive plant 1. It does not depend on the direction of stimulus applied. 2. Touch is the stimulus. 3. Caused by the sudden loss of water from the swellings at the base of leaves. 4. Occurs very fast Movement of a shoot towards light 1. Depends on the direction of stimulRead more
Movement of leaves of the sensitive plant
1. It does not depend on the direction of stimulus applied.
2. Touch is the stimulus.
3. Caused by the sudden loss of water from the
swellings at the base of leaves.
4. Occurs very fast
Movement of a shoot towards light
1. Depends on the direction of stimulus applied.
2. Light is the stimulus.
3. Caused by the unequal growth on the two sides of the shoot.
4. Occurs slowly.
See lessWhat are plant hormones? Name a plant hormone that promotes growth in plants.
Plant hormones are the organic substances produces at certain sites of the plant and are translocated to other parts based on the requirement. Plant hormones help to coordinate growth, development and responses to the environment. Ex: Auxin’s Gibberlin’s, cytokines, abscisic acid and ethylene.
Plant hormones are the organic substances produces at certain sites of the plant and are
See lesstranslocated to other parts based on the requirement. Plant hormones help to coordinate growth, development and responses to the environment. Ex: Auxin’s Gibberlin’s, cytokines, abscisic acid and ethylene.